A timeless dessert that’s as rich in history as it is in flavor. This chocolate sheet cake became a community favorite when it appeared in early Junior League cookbooks—especially the Denver edition. It’s everything you want in a homemade cake: moist, fudgy, and topped with a luscious cocoa frosting. Add some chopped nuts on top for a bit of crunch if you like!
🧾 Ingredients
For the Cake
Ingredient
Amount
All-purpose flour
2½ cups (plus extra for dusting)
Granulated sugar
2 cups
Baking soda
1 teaspoon
Salt
¼ teaspoon
Unsalted butter, cubed
2 sticks (plus extra for greasing)
Dutch cocoa powder, sifted
½ cup
Water
1½ cups
Buttermilk
½ cup
Eggs, lightly beaten
2
Vanilla extract
1½ teaspoons
For the Frosting
Ingredient
Amount
Unsalted butter
1 stick
Dutch cocoa powder, sifted
½ cup
Buttermilk
6 tablespoons
Vanilla extract
1 teaspoon
Salt
¼ teaspoon
Powdered sugar
3½ cups
Chopped walnuts or pecans (optional)
½ cup
👩🍳 Instructions
To Make the Cake:
Preheat the Oven Set your oven to 350°F (175°C). Grease and flour a 9×13-inch cake pan.
Combine Dry Ingredients In a large bowl, whisk together the flour, sugar, baking soda, and salt. Set aside.
Make Cocoa Mixture In a saucepan over medium-low heat, combine the butter, cocoa powder, and water. Stir until the butter is melted and the mixture is smooth.
Mix the Batter Pour the warm cocoa mixture into the bowl with dry ingredients and stir just until combined. Add buttermilk, eggs, and vanilla extract. Mix gently until smooth and well blended.
Bake Pour the batter into the prepared pan and bake for 28 to 32 minutes, or until a toothpick inserted in the center comes out clean. Let the cake cool fully in the pan before frosting.
To Make the Frosting:
Heat and Whisk In a small saucepan, melt the butter over medium-low heat. Whisk in the cocoa powder and buttermilk, and cook for about 1 minute until the mixture thickens slightly.
Finish the Frosting Remove from heat. Stir in vanilla, salt, and powdered sugar, whisking until smooth and glossy.
Frost the Cake While the frosting is still warm, pour it over the cooled cake and spread it evenly with a spatula. If using, sprinkle chopped nuts over the top.
Let It Set Allow the frosting to firm up for at least 1 hour before slicing. Cut into 15 squares and serve.
