Denver Chocolate Sheet Cake

There are few desserts as comforting and nostalgic as a classic chocolate sheet cake, and the Denver Chocolate Sheet Cake is one that has stood the test of time. Known for its simplicity and rich chocolate flavor, this cake first gained popularity when Junior League cookbooks began making their way into kitchens across America. The Denver edition featured this decadent treat, and it quickly became a staple at potlucks, birthdays, and family gatherings.

What makes this cake so special is its no-fuss preparation. Unlike layer cakes that require meticulous assembly, the Denver Chocolate Sheet Cake delivers maximum flavor with minimal effort. Baked in a simple 9×13 pan and topped with a silky chocolate frosting, it’s the kind of dessert you can make on a whim and count on to impress. Moist, fudgy, and finished with optional crunchy walnuts or pecans, it’s a timeless recipe that still feels fresh today.

Ingredients

For the Cake

• 2 ½ cups all-purpose flour, plus extra for dusting the pan

• 2 cups granulated sugar

• 1 teaspoon baking soda

• ¼ teaspoon salt

• 2 sticks unsalted butter, cubed, plus extra for greasing

• ½ cup Dutch cocoa powder, sifted

• 1 ½ cups water

• ½ cup buttermilk

• 2 eggs, lightly beaten

• 1 ½ teaspoons vanilla extract

For the Frosting

• 1 stick unsalted butter

• ½ cup Dutch cocoa powder, sifted

• 6 tablespoons buttermilk

• 1 teaspoon vanilla extract

• ¼ teaspoon salt

• 3 ½ cups powdered sugar

• ½ cup chopped walnuts or pecans (optional)

Instructions

Make the Cake

1. Preheat your oven to 350°F (175°C). Grease and flour a 9×13-inch cake pan.

2. In a large mixing bowl, whisk together flour, sugar, baking soda, and salt. Set aside.

3. In a small saucepan, combine butter, cocoa powder, and water. Heat over medium-low, whisking until the butter melts and the mixture is smooth.

4. Pour the cocoa mixture into the dry ingredients and stir until just combined.

5. Add buttermilk, eggs, and vanilla. Mix gently until the batter is smooth.

6. Pour into the prepared pan and bake for 28–32 minutes, or until a toothpick inserted in the center comes out clean.

7. Let the cake cool completely in the pan before frosting.

Make the Frosting

1. In a small saucepan, melt the butter over medium-low heat.

2. Add the cocoa powder and buttermilk, whisking constantly for 1 minute until the mixture resembles thin pudding.

3. Remove from heat and stir in vanilla, salt, and powdered sugar until smooth.

4. Immediately pour the warm frosting over the cooled cake and spread evenly.

5. Sprinkle with chopped nuts if desired.

6. Allow the frosting to set for at least 1 hour before slicing into 15 squares.

Why This Cake is a Classic

The Denver Chocolate Sheet Cake is proof that simplicity can be extraordinary. Its tender crumb, fudgy chocolate flavor, and glossy frosting make it a dessert that never goes out of style. Whether you serve it at a casual family dinner or bring it to a potluck, this cake delivers pure chocolate comfort with every bite.

It’s more than just a recipe—it’s a little piece of culinary history that still delights generations today.