Ultimate Moist One-Layer Chocolate Sheet Cake with Fudgy Sour Cream Frosting
Welcome to your new favorite recipe for an incredibly simple and supremely moist **one-layer chocolate cake**! Baked perfectly in a standard 9×13-inch pan, this delightful chocolate sheet cake is crowned with the best chocolate sour cream frosting you’ll ever taste. Forget complicated layers or elaborate decorating skills; this single-layer chocolate cake delivers on flavor, texture, and ease, making it ideal for any occasion. Its exceptional moistness and soft crumb are due to a thoughtful combination of buttermilk and neutral oil, ensuring a tender bite every time. Perfect with a generous scattering of colorful sprinkles, many consider this the ultimate birthday cake, potluck dessert, or simple family treat!
As a passionate baker, I have a deep love for all my chocolate cake recipes (hello, classic Matilda’s chocolate cake!). However, I frequently received questions and requests from readers wondering how to transform my beloved chocolate cake with vanilla frosting into a convenient sheet cake format. Listening to your feedback, I adapted my tried-and-tested chocolate cake recipe, baking it in a 9×13-inch pan, and voilà – the **perfect chocolate buttermilk sheet cake** was born!
This effortless chocolate sheet cake is a game-changer for gatherings. It’s incredibly versatile and wonderfully suited for birthday parties, casual potlucks, bustling bake sales, or festive holiday celebrations (simply switch up the sprinkle colors to match the season!). When you need to serve a crowd without the stress of intricate decorating, this easy chocolate cake is your go-to solution. It consistently delivers a rich, satisfying chocolate flavor and a delightfully moist texture that everyone will adore.
If you’re craving a vanilla alternative, be sure to explore my chocolate chip vanilla sheet cake recipe! Interestingly, it uses the same amazing chocolate sour cream frosting, proving just how adaptable and delicious this frosting is. One of the greatest advantages of baking a sheet cake is that it **doesn’t demand professional-level frosting skills** or specialized tools like piping bags and turntables. This is just a **good old-fashioned sheet cake** that promises exceptional taste and a charming, rustic appearance that’s sure to bring smiles.
Why This One-Layer Chocolate Cake Will Be Your New Favorite
There are countless reasons to fall in love with this particular chocolate sheet cake recipe. First and foremost, its simplicity is unmatched. You don’t need to be an experienced baker to achieve stunning results. The one-layer format means less fuss and quicker assembly, making it accessible for bakers of all skill levels. Secondly, the texture is truly superior – thanks to the combination of buttermilk and neutral oil, this cake remains incredibly moist and tender for days, resisting the common pitfall of dry chocolate cakes. Lastly, the fudgy chocolate sour cream frosting elevates this simple cake to a gourmet experience, offering a perfect balance of richness and a subtle tangy note that cuts through the sweetness beautifully. It’s a fuss-free dessert that tastes utterly decadent!
Essential Ingredients for Your Perfect Sheet Cake
Creating this spectacular chocolate sheet cake starts with selecting the right ingredients. Each component plays a vital role in achieving the cake’s signature moistness, rich flavor, and perfect texture. Let’s take a closer look at some key players:
- Dutch-Processed Cocoa Powder: This is a non-negotiable ingredient for achieving that deep, dark, and rich chocolate flavor we all crave. Unlike natural cocoa powder, Dutch-processed cocoa has been treated with an alkali to neutralize its acidity. This results in a darker color, a milder flavor profile, and it reacts differently with leavening agents. If you’re unsure which type you have, check the label for “alkali” or “acidity regulators” – that’s your clue it’s Dutch-processed. Using the correct cocoa powder ensures the cake rises properly and has the intended profound chocolate taste.
- Neutral Oil: The secret to a cake that stays soft and moist for an extended period lies in using a neutral oil instead of butter. While butter offers a wonderful flavor, oil provides unparalleled moisture retention, keeping your cake tender and delicious for DAYS! Opt for oils with a mild flavor and aroma such as vegetable oil, canola oil, or sunflower oil, so they don’t overpower the rich chocolate notes of the cake.
- Buttermilk: Buttermilk is a superstar ingredient in this chocolate sheet cake. Its acidity reacts with the baking soda to create a beautifully tender crumb and helps the cake rise perfectly. Furthermore, buttermilk contributes a subtle tang that beautifully complements the sweetness of the chocolate, adding depth to the flavor profile. Cocoa powder can sometimes lead to dry baked goods, but the inclusion of buttermilk actively works to keep this cake exceptionally moist and soft. If you don’t have buttermilk on hand, don’t worry, there’s an easy substitute you can make at home (see our notes section below!).
- Hot Water: Incorporating very hot water (or coffee!) into the batter at the end is crucial. It blooms the cocoa powder, intensifying its chocolate flavor and contributing to the cake’s incredibly moist texture. It also helps to create a thinner batter, which results in a wonderfully tender cake.
Baking Your Perfect Chocolate Sheet Cake: Step-by-Step
Making this incredible one-layer chocolate cake is surprisingly straightforward, requiring minimal effort for maximum deliciousness. Follow these simple steps to bake a moist and flavorful treat that will impress everyone.
- Step 1: Prepare Your Pan and Dry Ingredients. Start by preheating your oven to the specified temperature (350°F/175°C) and preparing your 9×13-inch baking pan. Lining it with parchment paper, creating a ‘sling’ with overhang, makes for easy removal later. In a large mixing bowl, whisk together all your dry ingredients – flour, cocoa powder, sugar, baking powder, baking soda, and salt. Ensure they are well combined to distribute the leavening evenly.
- Step 2: Combine Wet and Dry Ingredients. In a separate jug, whisk together your wet ingredients: buttermilk, oil, eggs, and vanilla extract. Then, gradually add this wet mixture into the dry ingredients in your large bowl. Mix until just smooth, being careful not to overmix, which can lead to a tough cake.
- Step 3: Incorporate Hot Water. This step is crucial for bloom and moisture! Slowly pour in the very hot water (or hot coffee for an even deeper flavor) and whisk until thoroughly combined. Don’t be alarmed by the consistency – the batter will be quite liquidy, which is exactly how it should be for an incredibly moist cake.
- Step 4: Bake and Cool. Pour the thin cake batter evenly into your prepared pan. Bake in the preheated oven for the recommended time, checking for doneness with a toothpick inserted into the center (it should come out clean). Once baked, let the cake cool completely in the pan before attempting to frost it. A fully cooled cake is essential for perfect frosting application!
Beyond Chocolate: Explore Alternative Frostings
While the rich, fudgy chocolate sour cream frosting is a match made in heaven for this moist chocolate sheet cake, you might occasionally crave a different flavor profile. Don’t limit yourself! This versatile chocolate cake pairs beautifully with a variety of frostings. Here are a few fantastic alternatives to consider if you’re looking for something other than chocolate on chocolate:
- Classic Vanilla Frosting – A timeless choice! A creamy, smooth vanilla buttercream provides a lovely contrast to the deep chocolate, offering a balanced and universally loved flavor.
- Biscoff Frosting – For a unique and incredibly delicious twist! The spiced, caramel notes of Biscoff cookie butter combined with rich chocolate cake is an unexpected pairing that will truly delight your taste buds. Sign me up!
- Tangy Cream Cheese Frosting – Oh, yes, this would be SO good! The slight tang and luxurious creaminess of cream cheese frosting cut through the richness of the chocolate cake perfectly, creating a sophisticated and irresistible dessert.
- Refreshing Mint Frosting – Giving strong “Thin Mints” vibes! The cool, invigorating flavor of mint frosting is a fantastic complement to chocolate, especially for those who love the classic chocolate-mint combination.
- Decadent Oreo Frosting – For those irresistible cookies and cream vibes! A chunky, creamy Oreo frosting adds another layer of texture and intense flavor, making this chocolate cake an absolute showstopper for cookie lovers.
Tips for a Flawless Chocolate Sheet Cake Every Time
Achieving a perfectly moist and delicious chocolate sheet cake is easier than you think, especially with a few expert tips. Here’s how to ensure your one-layer chocolate cake turns out beautifully every single time:
- **Room Temperature Ingredients are Key:** This cannot be stressed enough! Ensure all your cold ingredients, especially the eggs, buttermilk, and butter (for the frosting), are at room temperature. This allows them to emulsify properly, creating a smooth, uniform batter and a perfectly textured cake and frosting. Plan ahead and pull them out at least an hour before you start baking.
- **Measure with Precision:** Baking is a science, and accurate measurements are crucial. I highly recommend using a kitchen scale for flour and cocoa powder to ensure precision, especially if you’re accustomed to metric measurements. While US customary cup measurements are provided, weighing ingredients (in grams) offers the most consistent results.
- **Don’t Overmix:** Once the wet and dry ingredients are combined, mix just until no streaks of flour remain. Overmixing develops the gluten in the flour, which can lead to a tough, dense cake. A gentle hand will yield a tender, soft crumb.
- **Pan Preparation is Critical:** Greasing and flouring your 9×13-inch pan, then lining it with parchment paper (creating a “sling” by leaving overhang on two sides), makes removing the cooled cake a breeze. This prevents sticking and ensures your beautiful one-layer chocolate cake comes out in one piece.
- **Cool Completely Before Frosting:** Patience is a virtue when it comes to frosting! Attempting to frost a warm cake will result in melted, messy frosting. Allow your chocolate sheet cake to cool completely on a wire rack – this can take a couple of hours – before applying the luscious chocolate sour cream frosting.
- **Adjusting Salt:** If you typically use fine table salt instead of kosher salt, remember that kosher salt crystals are larger and less dense. As a general rule, you should halve the amount of salt called for if using fine salt (e.g., 1 teaspoon kosher salt = ½ teaspoon fine salt).
Storage and Make-Ahead Tips for Your Moist Chocolate Cake
One of the many benefits of this one-layer chocolate sheet cake is its excellent keeping qualities, thanks to the buttermilk and oil. It’s perfect for making ahead, which is a lifesaver when planning for parties or busy weeks. Here’s how to properly store your cake and prepare it in advance:
- **Storage:** To keep your frosted chocolate sheet cake at its best, ensure it is tightly wrapped or stored in an airtight container. It will stay wonderfully fresh in the refrigerator for up to 5 days. For the best flavor and texture experience, always allow the cake to come to room temperature for about 30 minutes before serving.
- **Making Ahead (Cake Only):** You can easily bake the cake layers (or in this case, the single sheet cake) ahead of time. Once the cake has completely cooled, wrap it very tightly in several layers of plastic wrap to prevent it from drying out.
- **Refrigeration:** Store the tightly wrapped cake in the fridge for up to 2 days.
- **Freezing:** For longer storage, you can freeze the unwrapped cake. Wrap it in plastic wrap, then an additional layer of aluminum foil to protect it from freezer burn. It can be frozen for up to 2 months.
- **Defrosting and Frosting:** If your cake has been frozen, allow it to defrost in the refrigerator overnight or at room temperature for several hours. Once fully defrosted and at room temperature, it will be ready for you to apply the delicious chocolate sour cream frosting. This make-ahead capability ensures you can enjoy a freshly frosted cake without the last-minute baking rush!
Craving More Easy & Delicious Party Cakes?
If you’ve fallen in love with the simplicity and deliciousness of this one-layer chocolate sheet cake, you’ll be thrilled to discover more fantastic recipes that are perfect for any celebration or casual treat. Explore these other crowd-pleasing cakes from our collection:
- Easy & Simple Chocolate Cake with Vanilla Frosting
- Chocolate Chip Sheet Cake with Chocolate Frosting
- Berry Vanilla Cake with Whipped Mascarpone Frosting
- Easy Funfetti Oreo Cake with Oreo Frosting
If you’ve made this incredibly moist **one-layer chocolate sheet cake** and delighted in its rich flavor, we would absolutely love to hear from you! Please **make sure to leave a ⭐️ rating and review below** to share your experience. Your feedback is invaluable and helps others discover this amazing recipe. I truly love seeing your creations, so don’t forget to tag me on Instagram @alpineella when you share your delicious results! You can also follow along for more baking inspiration on Pinterest, Facebook, and TikTok!
Recipe
One Layer Chocolate Cake (Sheet Cake)
Ella Gilbert
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Equipment
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1 9×13-inch cake pan
Ingredients
Chocolate Cake
- ¾ cup cocoa powder dutch processed
- 1 ¾ cups granulated sugar
- ¾ teaspoon vanilla extract
- ¾ teaspoon kosher salt
- 2 eggs room temperature
- 2 cups all purpose flour
- 2 teaspoon baking soda
- 1 teaspoon baking powder
- 1 cup buttermilk room temperature
- ½ cup vegetable oil
- 1 cups very hot water
Chocolate Sour Cream Frosting
- ½ cup unsalted butter room temperature
- pinch kosher salt
- 1 cup confectioners’ sugar
- ½ cup cocoa powder dutch processed
- ¼ cup sour cream room temperature
- 3 oz dark chocolate chopped
Instructions
Make Cake
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Preheat your oven to 350°F/175°C. Butter or grease a 9×13-inch cake pan and then line with parchment paper. I recommend making a ‘sling’, so you have parchment paper overhanging, to make it easier to get the cake out!
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Combine the flour, cocoa powder, sugar, baking powder, baking soda, and salt in a large bowl with a whisk.¾ cup cocoa powder, 1 ¾ cups granulated sugar, 2 cups all purpose flour, 2 teaspoon baking soda, 1 teaspoon baking powder, ¾ teaspoon kosher salt
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In a large jug, whisk together the buttermilk, oil, eggs, and vanilla extract.¾ teaspoon vanilla extract, 1 cup buttermilk, ½ cup vegetable oil, 2 eggs
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Slowly pour in the ingredients from the large jug and mix until just combined.
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Slowly add the hot water and mix. Your batter will be very thin and it makes a lot of cake batter!1 cups very hot water
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Pour the batter into the prepared pans. Bake for 35-40 minutes, until a toothpick comes out clean when inserted
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Allow the cakes to cool for 10 minutes before removing from the pan. Let them cool completely on a cooling rack.
Make Frosting
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Melt your chocolate in a microwave, stirring every 10 seconds so it doesn’t burn.3 oz dark chocolate
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In your stand mixer with the paddle attachment, or in a bowl with a handheld mixer, beat the butter and confectioners’ sugar on low speed until well combined½ cup unsalted butter, 1 cup confectioners’ sugar
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Turn the speed to high for 2-3 minutes until light and fluffy.
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Add in your cocoa powder and beat on low, then increase the speed to medium for 1-2 minutes.½ cup cocoa powder
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Add your sour cream, melted chocolate and salt and mix once more.¼ cup sour cream, 3 oz dark chocolate, pinch kosher salt
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Frost your cooled cake and enjoy!
Video
Notes
I make sure that all of my ingredients are at room temperature before I start the recipe, so pull out all of the ingredients before you start baking.
Cake Pan: I’m using a 9×13-inch cake pan from NordicWare with tall sides (like I would use for brownies or cinnamon rolls), and not a quarter sheet pan. This recipe would have slightly too much batter for a quarter sheet pan.
Salt: If you don’t have kosher salt, halve the amount of salt called for in the recipe. 1 teaspoon kosher salt = ½ teaspoon fine salt.
Buttermilk: If you don’t have buttermilk, replace it with an equal amount of sour cream or full fat yogurt. You can also make your buttermilk, for every cup of buttermilk add 1 tablespoon of lemon juice to 1 cup of milk and let sit for 5 minutes.
Sour Cream: I haven’t tested this frosting with a sour cream substitute, but you could probably get away with using Greek yogurt or full-fat yogurt!
Vegetable Oil: Use an unflavoured oil like canola oil if you don’t have vegetable oil.
Storage: Keep tightly wrapped in the fridge for up to 5 days. Let it come to room temperature before eating.
Making Ahead: You can make the cake ahead of time. Bake and then once completely cooled, wrap in plastic wrap tightly. Store in the fridge for up to 2 days or in the freezer for up to 2 months. If frozen, allow to defrost and come to room temperature before frosting the cake.
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