Decadent 9×13 Buttermilk Chocolate Sheet Cake with Fudgy Buttercream

Indulge in the ultimate chocolate experience with this incredibly moist and rich 9×13 buttermilk chocolate sheet cake. This recipe makes baking an irresistible chocolate cake surprisingly easy, delivering a dense, tender crumb bursting with deep cocoa flavor. Crowned with a luxurious, fudgy chocolate buttercream, this sheet cake is perfect for any occasion, from casual family gatherings to special celebrations. Get ready to impress everyone with this remarkably simple yet utterly delicious dessert that chocolate lovers will adore!

For those who love a classic chocolate cake but prefer the ease of a sheet cake, this recipe is a game-changer. I recently whipped up this 9×13 chocolate buttermilk cake from scratch in under two hours, proving that a truly decadent dessert doesn’t have to be complicated. Its straightforward preparation makes it an ideal choice for busy bakers or anyone looking for a quick yet impressive treat. With a fluffy, moist texture and an incredibly rich chocolate flavor, it’s a guaranteed crowd-pleaser.

If you’re a chocolate enthusiast, you’re in the right place! Beyond this fantastic sheet cake, here are some other chocolate-inspired recipes you absolutely must try:

• Chocolate Dipped Strawberry Cake
• The Best Ever Chocolate Salted Caramel Cake
• The Best and Irresistible Cookie Dough Cake

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Key Ingredients for Your Chocolate Cake Success

To ensure your 9×13 chocolate cake turns out perfectly, I’ve highlighted some key ingredients that might require a quick trip to the store or a check of your pantry. You’ll find the complete list of ingredients with precise measurements in the recipe card at the bottom of this page.

• Dark Cocoa Powder: For an incredibly deep and complex chocolate flavor, I recommend using a blend of half dark cocoa powder and half regular unsweetened cocoa powder. The dark cocoa intensifies the richness, giving the cake a beautiful color and a more sophisticated taste. I source my preferred dark cocoa from Amazon, which you can find here.
• Baking Powder & Baking Soda: These leavening agents are crucial for giving your cake its perfect rise and tender texture. To ensure maximum freshness and effectiveness, I always replace my containers of baking powder and baking soda monthly. Fresh leavening agents are key to a consistently fluffy cake.
• Buttermilk: The secret weapon for an incredibly moist and tender crumb! The acidity in buttermilk reacts with the baking soda, contributing to the cake’s lift and distinct, rich flavor profile. Using room temperature buttermilk is important for proper emulsification with other ingredients.
• Oil: Vegetable oil is my go-to for this recipe. It contributes to the cake’s moistness without adding a strong flavor, ensuring the chocolate is the star.
• Eggs: Always use room temperature eggs when baking. This allows them to emulsify more easily with other ingredients, creating a smoother batter and a better overall texture in the final cake. Take them out of the fridge a couple of hours before you plan to start baking.
• Hot Water: Don’t skip this! Adding hot water to the cocoa powder helps “bloom” the chocolate flavor, intensifying its depth and aroma significantly. It’s a simple step that makes a big difference.
• Heavy Cream: Essential for the luscious chocolate ganache that forms the base of our fudgy buttercream. Using heavy whipping cream ensures a rich and creamy texture.
• Dark Chocolate Wafers: For the most decadent buttercream, using high-quality dark chocolate wafers makes all the difference. Their rich flavor and smooth melting properties create a truly irresistible frosting.

Why You Will Adore This 9×13 Buttermilk Chocolate Cake

This isn’t just another chocolate cake recipe; it’s a meticulously crafted experience designed to deliver maximum flavor and ease. Here’s why this buttermilk chocolate sheet cake will quickly become a staple in your baking repertoire:

• Unbelievably Moist Chocolate Cake: Who doesn’t crave a cake that’s perfectly moist and tender? The secret to these incredibly plush cake layers lies in the combination of buttermilk and hot water. The hot water helps “bloom” the cocoa powder, intensifying the chocolate flavor, while the buttermilk’s acidity tenderizes the crumb, resulting in a cake that practically melts in your mouth. Furthermore, by using a blend of dark and regular cocoa, we achieve a profound depth of flavor that’s truly unforgettable.
• Effortlessly Easy to Make: Forget complicated techniques and endless bowls! This easy 9×13 chocolate cake is designed for simplicity. With minimal fuss, you’ll be able to create a stunning dessert. The process involves just a few straightforward steps: sifting your dry ingredients, whisking the wet ingredients, and then gently combining them. It’s so forgiving, it’s genuinely hard to mess up, making it perfect for novice bakers and seasoned pros alike.
• Luxurious Fudgy Buttercream: A chocolate cake is only as good as its frosting, and this fudgy buttercream takes it to another level. It’s exceptionally rich, smooth, and boasts a deep chocolate flavor that perfectly complements the moist cake. Its fudgy texture is a dream to spread and creates a truly decadent topping that elevates every bite.
• The Perfect Dessert for Any Occasion: This versatile 9×13 sheet cake is ideal for virtually any event. Whether you’re preparing a dessert for a special family get-together, celebrating a birthday, hosting a potluck, or simply craving a delightful weeknight treat, this cake fits the bill. Its generous size is perfect for feeding a crowd, ensuring everyone gets a slice of happiness.
• A Chocolate Lover’s Paradise: For true chocolate connoisseurs, this cake is a dream come true. Crafted with a significant amount of rich cocoa powder (including dark cocoa), it delivers an intense, complex chocolate experience that will satisfy even the most ardent chocoholic. Every bite is a journey into deep, luxurious chocolate flavor.
• Sheet Cake Convenience: The 9×13 sheet cake format offers unparalleled convenience. It’s easy to bake, simple to frost, and incredibly straightforward to slice and serve. Unlike multi-layer cakes, sheet cakes are also much easier to transport, making them ideal for picnics, parties, or bringing to a friend’s house.

Step-by-Step Instructions: Baking Your Perfect Chocolate Sheet Cake

Creating this delicious buttermilk chocolate cake is a simple and rewarding process. Follow these detailed steps for a flawless result:

1. Prepare for Baking: Preheat your oven to 350°F (175°C) for at least 30 minutes to ensure a consistently hot baking environment. Take your eggs and buttermilk out of the fridge approximately 2 hours before you plan to start, allowing them to reach room temperature. This is a crucial step for achieving a better rise and a more tender crumb. Prepare a 9×13-inch metal baking pan by lightly greasing the bottom, lining it with parchment paper, and then greasing the parchment paper as well. If needed, use metal binder clips to secure the parchment paper to the pan edges – remember to use metal, not plastic, as plastic will melt in the oven. Set the prepared pan aside.
2. Mix the Dry Ingredients: In the bowl of your stand mixer, fitted with the paddle attachment, meticulously sift together the all-purpose flour, granulated sugar, cocoa powder (both dark and regular), baking soda, baking powder, and salt. Sifting helps prevent lumps and ensures all ingredients are evenly distributed. Mix these dry ingredients on the lowest speed for just about 30 seconds, or until they are thoroughly combined.
3. Combine the Wet Ingredients: In a separate medium-sized bowl, whisk together the room temperature eggs, buttermilk, vegetable oil, and pure vanilla extract until they are well blended. Once combined, slowly and carefully pour in the hot water, whisking continuously as you add it. It’s important to add the hot water gradually to prevent the eggs from cooking or scrambling.
4. Integrate Wet and Dry: With your stand mixer running on the lowest speed, slowly pour the combined wet ingredients into the dry ingredient mixture. Mix just until the ingredients are fully incorporated and no streaks of flour remain. Be careful not to overmix, as this can lead to a tough cake. Stop the mixer, and use a rubber spatula to scrape down the sides and bottom of the bowl, ensuring all components are thoroughly mixed and evenly distributed.
5. Prepare for Baking: Pour the smooth cake batter evenly into your prepared 9×13-inch baking pan. Use the back of a spoon or an offset spatula to gently spread the batter and ensure a perfectly level surface. This helps the cake bake evenly and rise beautifully.
6. Bake to Perfection: Place the cake in your preheated oven and bake for 40-45 minutes. To check for doneness, insert a toothpick into the center of the cake. It should come out with just a few moist crumbs clinging to it, indicating that the cake is perfectly baked without being dry.
7. Cool Completely: Once baked, remove the cake from the oven and allow it to cool completely in the cake pan on a wire rack. This is a critical step; frosting a warm cake will cause the buttercream to melt and slide off. While the cake is cooling, you can proceed with making the decadent chocolate buttercream.

Step-by-Step Instructions: Crafting the Fudgy Chocolate Buttercream

This rich and decadent buttercream is the perfect companion to your buttermilk chocolate cake. Follow these steps carefully for a smooth, fudgy frosting:

1. Melt the Chocolate: In a microwave-safe bowl, heat your dark chocolate wafers for 30 seconds. Remove and stir well. Heat for another 30 seconds, then stir again. The chocolate might not be completely melted at this point, but it will be sufficiently warm to easily melt when combined with the hot cream, preventing seizing. Set aside.
2. Heat and Pour the Cream: In a separate microwave-safe bowl, heat the heavy cream until it’s just about to boil (you’ll see small bubbles around the edges). Be careful not to let it boil over. Once hot, immediately pour the heated cream over the slightly warm chocolate chips. Allow the mixture to sit undisturbed for 2 minutes. This allows the hot cream to gently melt the chocolate. After 2 minutes, stir the mixture vigorously until it’s smooth and glossy, forming a rich ganache. Set this chocolate ganache aside to cool slightly.
3. Beat the Butter: In the bowl of a stand mixer fitted with the paddle attachment, beat the slightly chilled unsalted butter on medium-high speed for approximately 2 minutes. The butter should become lighter in color and fluffy, which is essential for a light and airy buttercream.
4. Incorporate the Ganache Mixture: With the mixer on low speed, gradually add the cooled chocolate ganache mixture to the beaten butter. Once fully incorporated, stop the mixer and use a rubber spatula to scrape down the sides and bottom of the bowl, ensuring all ingredients are well combined. Beat for 1 more minute on medium speed until smooth.
5. Add Remaining Ingredients: Reduce the mixer speed to low. Gradually add the sifted powdered sugar, cocoa powder, vanilla extract, and salt. Start slowly to avoid a cloud of powdered sugar! Once these ingredients are mostly combined, increase the mixer speed to medium-high and beat for an additional 3 minutes. This will make the buttercream light, fluffy, and incredibly smooth.
6. Remove Air Pockets: To achieve an ultra-smooth, professional-looking buttercream, turn off the mixer. Using a wooden spoon or a sturdy rubber spatula, manually stir and press the buttercream against the sides of the bowl for a few minutes. This process helps to work out any air pockets that might have been incorporated during mechanical mixing.

Hint: If you plan to add intricate piping or decorative elements to the top of your cake, consider making an additional half batch of this delicious buttercream to ensure you have plenty.

Expert Baking Tips for Your Buttermilk Chocolate Cake

Even though this recipe is straightforward, a few expert tips can elevate your 9×13 chocolate buttermilk cake from great to absolutely extraordinary:

• Room Temperature Ingredients are Key: As mentioned in the recipe, ensuring your eggs and buttermilk are at room temperature is non-negotiable. Cold ingredients don’t emulsify as well, leading to a lumpy batter and a denser, less uniform cake crumb. Plan ahead and take them out a couple of hours before you start baking.
• Invest in Quality Cake Pans: A good quality baking pan makes a significant difference. Thicker, lighter-colored metal pans conduct heat more evenly, preventing burnt edges and ensuring a consistent bake. My favorite pan for sheet cakes can be found here.
• Always Preheat Your Oven Thoroughly: Don’t rush this step! Give your oven a full 20-30 minutes to preheat and reach the target temperature. Opening the oven door too soon or baking in an underheated oven can lead to a deflated or unevenly baked cake.
• Measure Flour Correctly: The “spoon and level” method is crucial for accurate flour measurement. Spoon the flour into your measuring cup until it overflows, then level it off with the back of a knife. Scooping directly from the bag can compact the flour, leading to too much flour and a dry cake.
• Do Not Overmix the Batter: Once you combine the wet and dry ingredients, mix only until just combined. Overmixing develops the gluten in the flour, resulting in a tough, chewy cake. A few small lumps are perfectly fine!
• Quality Cocoa Matters: The type of cocoa powder you use significantly impacts the final flavor. Opt for a high-quality cocoa powder, especially if you’re using a mix of dark and regular, to ensure a rich and nuanced chocolate taste.
• Parchment Paper for Easy Release: Always use parchment paper in your baking pan. Not only does it prevent sticking, but it also makes removing the cooled cake incredibly easy and ensures a clean presentation.

FAQ: 9×13 Buttermilk Chocolate Cake

Here are answers to some common questions about this versatile and delicious chocolate sheet cake:

Can I make this recipe into cupcakes?

Yes, absolutely! This recipe works beautifully for cupcakes. It will yield approximately 18-20 standard-sized cupcakes. You’ll need to reduce the baking time significantly, typically to about 20-22 minutes. Keep an eye on them and test with a toothpick for doneness.

Can this be made into a layer cake?

This recipe is highly adaptable and can certainly be transformed into a stunning layer cake. You can make a four-layer, 6-inch cake, or a three-layer, 8-inch cake. If you opt for a layer cake, remember that you will need to double the amount of frosting ingredients to ensure generous coverage between layers and on the outside of the cake.

What if I don’t have buttermilk? Can I make my own?

Yes! If you don’t have buttermilk on hand, you can easily make a substitute. For 1 cup of buttermilk, pour 1 tablespoon of lemon juice or white vinegar into a liquid measuring cup. Then, fill the rest of the cup with regular milk (dairy or non-dairy) until it reaches the 1-cup line. Stir gently and let it sit for 5-10 minutes until it curdles slightly. This homemade version works perfectly in this recipe.

Can I use only dark cocoa powder?

While the recipe calls for a blend, you can use only dark cocoa powder if you prefer an even more intense, less sweet, and bolder chocolate flavor. Just be aware that it might result in a slightly darker cake with a more robust, almost bitter, chocolate profile. Always use unsweetened cocoa powder.

How can I prevent my chocolate cake from drying out?

Several factors contribute to a moist cake: using room temperature ingredients, not overmixing the batter, and not overbaking. Buttermilk is a fantastic ingredient for moisture, as is oil. Make sure to check the cake for doneness with a toothpick and remove it from the oven as soon as it’s ready, even if it’s a minute or two before the suggested time.

Storing and Freezing Your 9×13 Buttermilk Chocolate Cake

Proper storage ensures your delicious buttermilk chocolate sheet cake remains fresh and enjoyable for as long as possible:

Storing This 9×13 Chocolate Cake

Store this 9×13 Buttermilk Chocolate Cake with Fudgy Buttercream in the fridge, well-covered with plastic wrap, for up to 5 days. For the best flavor and texture, allow the cake to come to room temperature for about 30-60 minutes before slicing and serving. This enhances its moistness and brings out the full depth of its chocolate flavor.

Freezing This 9×13 Chocolate Cake With Buttermilk

This chocolate sheet cake freezes exceptionally well! You can freeze it for up to 6 months. To do so, ensure the cake is completely cooled. Wrap it tightly in several layers of plastic wrap, then an additional layer of aluminum foil, making sure it is entirely airtight. You can freeze it frosted or unfrosted. Thaw overnight in the refrigerator before bringing it to room temperature for serving.

If you make this recipe, please make sure to rate and leave a review! Your feedback is invaluable and helps others discover this amazing chocolate cake.

Looking for more delightful sheet cake or 9×13 recipes? Explore these other fantastic options:

Recipe Card

Chocolate Cake

Molly Murphy

moist and dense chocolate cake made easy with a sheet cake form. Topped with a rich and decadent chocolate buttercream.

5 from 2 votes

Print Recipe
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Course Dessert

Cuisine Cake

Servings 12

Ingredients

 

 

For the chocolate cake

• 3 eggs room temperature
• 1 cup buttermilk room temperature
• 1 cup hot water
• ½ cup vegetable oil
• 2 cups all-purpose flour spooned and leveled.
• 1 ¾ cups granulated sugar
• ¾ cup dark cocoa powder
• 2 teaspoons baking soda
• 2 teaspoons baking powder
• 1 teaspoon salt
• 1 Tablespoon pure vanilla extract

For the fudgy buttercream

• ¾ cups unsalted butter slightly chilled
• ¾ cup unsweetened baking cocoa sifted
• 1 teaspoon salt
• 4 ½ cups powdered sugar sifted
• 1 teaspoon vannilla extract
• ½ cup heavy cream
• 2 cups dark chocolate

Instructions

 

For the cake

• Preheat your oven to 350 degrees. Spray a 9×13 metal pan on the bottom, line with parchment paper, and spray again. If you need to use metal binder clips to hold down the sides, remember to use metal, not plastic. Set aside
• In a stand sized mixer fitted with the paddle attachment, combine the flour, sugar, cocoa powder, baking soda, baking powder, and salt. Mix on low until evenly combined.
• In a small bowl, whisk the eggs, buttermilk, hot water, vanilla extract, and vegetable oil until evenly combined.
• With the mixer on the lowest speed, pour the liquid ingredients into the dry ingredients and mix just until combined. There should be no flour streaks. With a rubber spatula, scrape the bottom of the bowl to make sure the batter is evenly combined.
• Evenly distribute the cake batter to the prepped cake pan. With the back of a spoon, even out the batter to ensure it’s smooth for baking.
• Bake for 40-45 minutes. Check the cake by inserting a toothpick. It’s done when it comes out with just a few moist crumbs on it.
• Let it completely cool in the cake pan. While the cake cools, make the chocolate buttercream.

For the fudgy buttercream

• In a microwave safe bowl, heat the chocolate for 30 seconds, stir, heat for 30 more seconds, and set aside. The chocolate will not be melted all the way, but this will help it melt quicker when you add the cream.
• In another microwave proof bowl, heat the cream until nearly boiling. Make sure it doesn’t boil over. Pour the hot cream over the slightly warm chocolate chips. Let it sit for 2 minutes and then stir. Set aside.
• In the bowl of a stand mixer fitted with the paddle attachment, beat the butter for about 2 minutes on medium-high speed.
• Add the chocolate/cream mixture. Scrape down the sides and bottom of the bowl with a rubber spatula and beat for 1 more minute.
• Add the powdered sugar, cocoa powder, vanilla, and salt. Mix on low until combined, then turn the mixer to medium high and beat for 3 minutes.
• With a wooden spoon or rubber spatula, beat by hand to mix out any air pockets.
• When the cake is cooled, use an offset spatula and frost the top of the cake. This cake is good served at room temperature or cold. However you serve it, it will not disappoint!

Keyword chocolate, sheetcake, fudgy

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