Chocolate Buttercream Sheet Cake

Name: Chocolate Buttercream Sheet Cake
Prep time: 20 min
Cook time: 30 min
Total time: 50 min
Yield: 12 servings
Ingredients: 2 cups all-purpose flour; 2 cups granulated sugar; 3/4 cup unsweetened cocoa powder; 1 1/2 tsp baking powder; 1 1/2 tsp baking soda; 1 tsp salt; 2 large eggs; 1 cup whole milk; 1/2 cup vegetable oil; 2 tsp vanilla extract; 1 cup boiling water; 1 cup unsalted butter, softened; 3 1/2 cups powdered sugar; 1/2 cup unsweetened cocoa powder; 1/4 cup heavy cream; 2 tsp vanilla extract

Highlighted under: Oven Food

I’ve always had a soft spot for chocolate desserts, but this Chocolate Buttercream Sheet Cake takes the cake, quite literally! It’s incredibly moist and flavorful, with a rich buttercream frosting that sends my taste buds soaring. Perfect for any occasion, I love how easy it is to whip up this decadent treat. Each bite is a delightful dance of chocolate that’s sure to impress friends and family. Just wait until you see their faces light up when they get a taste of this delicious creation!

Created by

Zadie Whitmore

Last updated on 2026-02-16T00:57:36.356Z

When I first tried my hand at this Chocolate Buttercream Sheet Cake, I was amazed at how simple yet satisfying it was to make. The secret lies in using high-quality cocoa powder, which elevates the chocolate flavor to a whole new level. Every slice is incredibly rich, and the fluffy buttercream adds just the right amount of sweetness. It’s a cake that never fails to impress!

What I love most about this recipe is its versatility. Whether you’re celebrating a birthday, hosting a gathering, or just want a treat for yourself, this cake is perfect. I often pair it with fresh berries for a delightful contrast, but it’s equally satisfying on its own. Give it a try, and I promise you won’t be disappointed!

Why You'll Love This Recipe
Rich chocolate flavor paired with fresh orange zest
Creamy texture that melts in your mouth
Perfect for celebrations or as a sweet indulgence

Understanding the Ingredients

Each ingredient in this Chocolate Buttercream Sheet Cake plays a crucial role in achieving the perfect texture and flavor. The all-purpose flour provides the structure necessary for the cake, while the granulated sugar not only adds sweetness but also contributes to a moist crumb. Cocoa powder offers that intense chocolate flavor which is essential for this dessert. Always use high-quality cocoa for a richer taste. Also, don't skip adding boiling water; it helps to bloom the cocoa and makes the cake incredibly moist.

Eggs are key to binding the ingredients together, giving the cake a lift and a light texture. If you’re looking for a vegan alternative, consider using flaxseed meal mixed with water as a substitute for eggs. For the buttercream frosting, use unsalted butter to control the salt levels, ensuring the frosting remains sweet and creamy without unexpected saltiness. Opt for a little extra heavy cream if you prefer a silkier texture in your frosting.

Mastering Techniques

When mixing the cake batter, be careful not to overmix after adding the boiling water. A few lumps are okay; they will soften during baking, resulting in a more tender cake. Use a rubber spatula to scrape down the sides of the bowl and ensure everything is well combined. For the frosting, begin beating the butter at a lower speed. Gradually incorporate the powdered sugar and cocoa to avoid a sugar cloud in your kitchen. Beat until the mixture is creamy before adding the cream and vanilla extract; this is crucial for achieving the desired fluffiness.

For the perfect frosting, allow the cake to cool completely on a wire rack. This prevents the frosting from melting and ensures a beautiful finish. I recommend using an offset spatula to spread the frosting evenly. If you like, you can chill the frosting for about 15 minutes for easier spreading or use a piping bag for a more decorative touch. Remember, a well-frosted cake not only tastes great but also makes a stunning centerpiece!

Ingredients

For the Cake

2 cups all-purpose flour
2 cups granulated sugar
3/4 cup unsweetened cocoa powder
1 1/2 tsp baking powder
1 1/2 tsp baking soda
1 tsp salt
2 large eggs
1 cup whole milk
1/2 cup vegetable oil
2 tsp vanilla extract
1 cup boiling water

For the Buttercream Frosting

1 cup unsalted butter, softened
3 1/2 cups powdered sugar
1/2 cup unsweetened cocoa powder
1/4 cup heavy cream
2 tsp vanilla extract

Instructions

Preparation Steps

Prepare the Cake

Preheat your oven to 350°F (175°C). Grease and flour a 13x18 inch baking sheet. In a large bowl, sift together flour, sugar, cocoa powder, baking powder, baking soda, and salt. Add eggs, milk, oil, and vanilla, beating until smooth. Gradually stir in boiling water until fully combined. Pour the batter into the prepared baking sheet and bake for 30 minutes or until a toothpick comes out clean.

Make the Buttercream Frosting

While the cake is baking, beat the softened butter until creamy. Gradually add powdered sugar and cocoa powder, mixing on low until combined. Add heavy cream and vanilla, and beat on high until fluffy and smooth.

Frost the Cake

Once the cake has cooled completely, frost it with the chocolate buttercream, spreading evenly across the top. Decorate with sprinkles or chocolate shavings if desired.

Serve slices at room temperature and enjoy!

Pro Tips

For an extra touch, add a hint of espresso powder to the cake batter for enhanced chocolate flavor!

Storage Tips

This Chocolate Buttercream Sheet Cake can be stored at room temperature for up to three days, provided it is kept in an airtight container. If you live in a particularly warm climate, it’s best to refrigerate the cake after frosting to prevent the buttercream from melting. In the fridge, it can last about a week, though the texture of the frosting may become slightly firmer. Bring the cake back to room temperature before serving for the best flavor and texture.

For longer storage, consider freezing the unfrosted cake. Wrap it tightly in plastic wrap, followed by aluminum foil, and it can last up to three months in the freezer. Make sure to label the wrap with the date you made it. When you're ready to enjoy a slice, thaw it overnight in the fridge, then bring it to room temperature before frosting.

Serving Suggestions

This cake is incredibly versatile when it comes to serving options. It can be enjoyed plain, adorned only with the luscious chocolate buttercream, or dressed up with seasonal fruits like raspberries or strawberries for a fresh contrast to the rich chocolate. If you're hosting a gathering, cut the cake into squares and serve them with a dollop of whipped cream or a scoop of vanilla ice cream to elevate the flavor experience.

For an extra touch, consider adding flavor variations to the frosting. A hint of orange zest pairs beautifully with chocolate and can be mixed in for an exciting twist. You could also experiment with different extracts, like peppermint for a festive flair, especially around the holidays. These simple enhancements can transform the whole cake experience and delight your guests!

Questions About Recipes

→ Can I make this cake ahead of time?

Yes, the cake can be baked a day ahead. Just store it tightly wrapped at room temperature until ready to frost.

→ What can I substitute for eggs?

You can use a flax egg (1 tablespoon of ground flaxseed mixed with 2.5 tablespoons of water) for each egg as a substitute.

→ Can I freeze this cake?

Yes! You can freeze the unfrosted cake for up to 3 months. Just wrap it well before placing it in the freezer.

→ Is there a gluten-free version of this recipe?

Absolutely! Substitute all-purpose flour with a gluten-free flour blend, and ensure your other ingredients are gluten-free.