Chocolate Buttercream Sheet Cake

Name: Chocolate Buttercream Sheet Cake
Prep time: 20 min
Cook time: 25 min
Total time: 45 min
Yield: 12 servings
Ingredients: 1 ¾ cups all-purpose flour; 2 cups granulated sugar; ¾ cup unsweetened cocoa powder; 1 ½ teaspoons baking powder; 1 ½ teaspoons baking soda; 1 teaspoon salt; 2 large eggs; 1 cup buttermilk; ½ cup vegetable oil; 2 teaspoons vanilla extract; 1 cup boiling water; ½ cup unsalted butter, softened; 3 ½ cups powdered sugar; ½ cup unsweetened cocoa powder; ¼ cup milk; 1 teaspoon vanilla extract

Highlighted under: Easy Desserts Ideas

I absolutely love making this Chocolate Buttercream Sheet Cake for my friends and family! It's moist, rich, and incredibly satisfying, perfect for any occasion. Each bite is bursting with decadent chocolate flavor, and that buttery frosting on top takes it to a whole new level. Whether it's a birthday or just a Sunday bake-off, this cake never fails to impress. I can’t wait to share the simple steps and tips that will make you a baking superstar with this treat!

Created by

Maribel Sutton

Last updated on 2026-02-16T10:32:51.724Z

During my journey of baking, I found that the secret to a truly delightful Chocolate Buttercream Sheet Cake lies in the balance of ingredients and the whisking technique. I meticulously blend the cocoa powder and sugar to ensure that every slice is filled with rich flavor. To keep the cake moist, I use buttermilk, which not only enhances the taste but also gives that soft crumb we all adore.

After many trials, I've perfected my buttercream frosting! It's crucial to beat the butter until fluffy before adding the sugar, which results in a creamy, velvety finish. Top it off with chocolate shavings or sprinkles, and this cake becomes a feast for both the eyes and the palate!

Why You Will Love This Recipe
Decadent chocolate flavor that satisfies every sweet tooth
Indentical soft crumb that stays moist for days
Simple steps make it a perfect baking project for any level

Perfecting Your Cake

Achieving a perfectly moist and rich cake is all about attention to detail. The use of buttermilk adds acidity, resulting in a tender crumb, while the addition of boiling water helps to bloom the cocoa, enhancing its flavor. Make sure to mix the batter only until combined – overmixing can lead to a dense cake. I recommend using room temperature ingredients, as they help the batter emulsify properly, yielding a smoother texture that's delightful with every bite.

Another key aspect is monitoring your baking time. Ovens can vary, so start checking for doneness a couple of minutes before the 25-minute mark. Insert a toothpick into the center; if it comes out with a few moist crumbs, the cake is done. Allowing the cake to cool completely before frosting is crucial, as even a warm cake can melt your buttercream, leaving a melty mess rather than a beautifully frosted dessert.

Crafting the Buttercream Frosting

The buttercream frosting elevates this cake to another level of decadent delight. For the best texture, ensure your butter is softened to room temperature; this will allow it to whip up light and creamy. Start beating the butter until it’s fluffy before gradually adding the powdered sugar and cocoa powder. This method helps to prevent a grainy frosting and ensures a silky finish that's easy to spread over your cake.

If your buttercream is too thick, add a tablespoon of milk at a time until you reach your desired consistency. Conversely, if the frosting is too runny, add a bit more powdered sugar until it thickens up. It’s also a good idea to give it a taste test; the balance of sweetness to cocoa is vital for achieving that perfect chocolate flavor that complements the cake without overwhelming it.

Ingredients

Gather the following ingredients for a scrumptious experience:

For the Cake:

1 ¾ cups all-purpose flour
2 cups granulated sugar
¾ cup unsweetened cocoa powder
1 ½ teaspoons baking powder
1 ½ teaspoons baking soda
1 teaspoon salt
2 large eggs
1 cup buttermilk
½ cup vegetable oil
2 teaspoons vanilla extract
1 cup boiling water

For the Buttercream Frosting:

½ cup unsalted butter, softened
3 ½ cups powdered sugar
½ cup unsweetened cocoa powder
¼ cup milk
1 teaspoon vanilla extract

Make sure you have everything ready before you start baking!

Instructions

Now, let's walk through the steps to make this delicious cake:

Preheat the Oven

Preheat your oven to 350°F (175°C) and grease a 9x13 inch baking pan.

Mix the Dry Ingredients

In a large bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt.

Combine the Wet Ingredients

Add the eggs, buttermilk, oil, and vanilla extract to the dry ingredients and mix until well combined.

Add Boiling Water

Stir in the boiling water until the batter is smooth (it will be thin).

Bake the Cake

Pour into the prepared pan and bake for 25 minutes or until a toothpick comes out clean.

Prepare the Buttercream

In a separate bowl, beat the softened butter until creamy. Gradually add powdered sugar and cocoa powder, alternating with milk, until it reaches desired consistency.

Frost the Cake

Once the cake is cool, spread the buttercream evenly on top. Optionally, garnish with chocolate shavings or sprinkles.

Enjoy your homemade Chocolate Buttercream Sheet Cake!

Pro Tips

For added flavor, consider folding in some chocolate chips into the cake batter before baking. This cake freezes well, so you can make it ahead of time for special occasions.

Storing and Freezing

If you have leftover cake, store it in an airtight container at room temperature for up to three days. To keep it fresh longer, consider refrigerating it, but let it come to room temperature before serving to enjoy the full flavor. If you adore this cake and want to bake it in advance, you can freeze the cake layers. Wrap each layer in plastic wrap tightly and store in the freezer for up to a month. When ready to enjoy, let the layers thaw in the fridge overnight before frosting.

As for the buttercream frosting, it can also be refrigerated in an airtight container for up to two weeks. Just remember to let it come to room temperature and re-whip it to restore its fluffy texture before using it again.

Serving Suggestions

This cake pairs beautifully with a scoop of vanilla ice cream or a dollop of whipped cream. For a fun twist, try serving it with fresh berries or a drizzle of chocolate syrup to elevate the dessert experience. If you’re looking to impress, consider adding a sprinkle of flaky sea salt over the frosting for a delightful contrast to the sweet chocolate flavors.

You can also customize this cake with flavor variations. Add a teaspoon of instant coffee granules to the boiling water to enhance the chocolate flavor. Alternatively, mix in a splash of peppermint extract for a festive twist during the holidays – it’ll elevate the chocolate flavor to new heights while providing a refreshing aftertaste.

Questions About Recipes

→ Can I use cake flour instead of all-purpose flour?

Yes, cake flour will create a lighter and fluffier texture.

→ How do I store leftovers?

Store the cake in an airtight container at room temperature for up to 3 days or in the refrigerator for up to a week.

→ Can I make this cake ahead of time?

Absolutely! The cake can be made a day in advance. Just frost it right before serving.

→ What can I substitute for buttermilk?

You can make your own buttermilk by mixing 1 cup of milk with 1 tablespoon of vinegar or lemon juice and letting it sit for 5 minutes.