Easy Chocolate Sheet Cake with Fudgy Chocolate Frosting

Looking for the perfect dessert that’s guaranteed to please a crowd? This easy chocolate sheet cake with decadent fudgy frosting is your answer! Made in just one pan, this moist and tender cake comes together quickly for parties, potlucks, or simple weeknight treats. The rich cocoa flavor and velvety frosting make it a family favorite that will have everyone asking for seconds.

Ingredients

For the Cake:

• 2 cups all-purpose flour
• 2 cups granulated sugar
• 1 teaspoon baking soda
• 1/2 teaspoon salt
• 1 cup unsalted butter
• 1 cup water
• 1/4 cup cocoa powder
• 2 large eggs
• 1/2 cup buttermilk
• 1 teaspoon vanilla extract

For the Fudgy Frosting:

• 1/2 cup unsalted butter
• 1/4 cup cocoa powder
• 6 tablespoons milk
• 1 teaspoon vanilla extract
• 3 1/2 cups powdered sugar
• 1 cup chopped walnuts or pecans (optional)

Step-by-Step Instructions

Making the Cake

1. Preheat your oven to 350°F (175°C). Grease and flour a 15×10-inch jelly roll pan or a 13×9-inch baking pan.
2. In a large bowl, whisk together flour, sugar, baking soda, and salt. Set aside.
3. In a medium saucepan, combine butter, water, and cocoa powder. Bring to a boil, stirring constantly.
4. Remove from heat and pour the chocolate mixture over the dry ingredients. Mix until well combined.
5. In a small bowl, beat eggs with buttermilk and vanilla. Add to the batter and mix until smooth.
6. Pour batter into prepared pan and bake for 20-25 minutes, or until a toothpick inserted in the center comes out clean.

Preparing the Frosting

1. While the cake is baking, prepare the frosting. In a medium saucepan, combine butter, cocoa powder, and milk.
2. Bring to a boil, stirring constantly, then remove from heat.
3. Stir in vanilla extract, then gradually beat in powdered sugar until smooth and creamy.
4. If using nuts, stir them into the frosting.

Assembling the Cake

1. As soon as the cake comes out of the oven, pour the warm frosting over the hot cake.
2. Spread evenly with a spatula to cover the entire surface.
3. Allow the cake to cool completely before cutting into squares and serving.

Expert Tips

• Pan Size Matters: For a thinner, more traditional sheet cake, use a 15×10-inch jelly roll pan. For a thicker cake, use a 13×9-inch pan and adjust baking time accordingly.
• Buttermilk Substitute: No buttermilk? Mix 1/2 cup milk with 1 1/2 teaspoons lemon juice or vinegar and let sit for 5 minutes.
• Frosting Consistency: If your frosting becomes too thick, add a teaspoon of milk at a time until desired consistency is reached.
• Make Ahead: This cake actually tastes better the next day as the flavors meld together beautifully.
• Storage: Store covered at room temperature for up to 3 days, or refrigerate for longer storage.

Frequently Asked Questions

Can I make this cake gluten-free?

Yes! Substitute the all-purpose flour with your favorite gluten-free flour blend. Make sure it contains xanthan gum or add 1 teaspoon to the dry ingredients.

How many servings does this recipe make?

This cake yields about 24 generous servings, making it perfect for large gatherings and potlucks.

Can I freeze chocolate sheet cake?

Absolutely! Freeze the unfrosted cake wrapped tightly in plastic wrap for up to 3 months. Thaw and frost before serving. The frosted cake can also be frozen, though the frosting texture may change slightly.

What makes this cake so moist?

The combination of buttermilk and the hot chocolate mixture poured over the dry ingredients creates an exceptionally moist and tender crumb that stays fresh for days.

Can I add other mix-ins to the cake?

Certainly! Try adding chocolate chips, chopped toasted nuts, or even a teaspoon of instant coffee to enhance the chocolate flavor.

Easy Chocolate Sheet Cake with Fudgy Chocolate Frosting

This easy chocolate sheet cake features a moist and tender cocoa cake topped with decadent fudgy frosting, all made in just one pan. Perfect for parties, potlucks, or weeknight treats, this crowd-pleasing dessert comes together quickly and yields generous servings.

Print Recipe Pin Recipe

Prep Time 20 minutes mins

Cook Time 25 minutes mins

Total Time 45 minutes mins

Servings: 24 servings

Calories: 320

Ingredients Method Notes

Ingredients

  

Ingredients

• 2 cups all-purpose flour
• 2 cups granulated sugar
• 1 teaspoon baking soda
• 1/2 teaspoon salt
• 1 cup unsalted butter
• 1 cup water
• 1/4 cup cocoa powder
• 2 large eggs
• 1/2 cup buttermilk
• 1 teaspoon vanilla extract
• 1/2 cup unsalted butter
• 1/4 cup cocoa powder
• 6 tablespoons milk
• 1 teaspoon vanilla extract
• 3 1/2 cups powdered sugar
• 1 cup chopped walnuts or pecans (optional)

Method

 

Instructions

1. Preheat your oven to 350°F (175°C). Grease and flour a 15×10-inch jelly roll pan or a 13×9-inch baking pan.
2. In a large bowl, whisk together flour, sugar, baking soda, and salt. Set aside.
3. In a medium saucepan, combine butter, water, and cocoa powder. Bring to a boil, stirring constantly.
4. Remove from heat and pour the chocolate mixture over the dry ingredients. Mix until well combined.
5. In a small bowl, beat eggs with buttermilk and vanilla. Add to the batter and mix until smooth.
6. Pour batter into prepared pan and bake for 20-25 minutes, or until a toothpick inserted in the center comes out clean.
7. While the cake is baking, prepare the frosting. In a medium saucepan, combine butter, cocoa powder, and milk.
8. Bring to a boil, stirring constantly, then remove from heat.
9. Stir in vanilla extract, then gradually beat in powdered sugar until smooth and creamy.
10. If using nuts, stir them into the frosting.
11. As soon as the cake comes out of the oven, pour the warm frosting over the hot cake.
12. Spread evenly with a spatula to cover the entire surface.
13. Allow the cake to cool completely before cutting into squares and serving.

Notes

For a thinner cake use 15×10-inch pan, for thicker use 13×9-inch. Buttermilk substitute: mix 1/2 cup milk with 1 1/2 tsp lemon juice. Cake tastes better the next day. Store covered at room temperature for 3 days or refrigerate.