How to Make Denver Chocolate Sheet Cake

Preheat the oven

Heat oven to 350°F (175°C). Grease a 9×13-inch or 10×15-inch baking pan.

Mix the dry ingredients

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

Prepare the hot mixture

In a saucepan, melt butter with water and cocoa powder. Bring just to a boil, then pour the hot mixture into the dry ingredients. Stir until combined.

Add wet ingredients

Beat in eggs, sour cream, and vanilla until smooth. The batter will be slightly thin—that’s normal.

Bake the cake

Pour into prepared pan and bake for 25–30 minutes, or until a toothpick comes out clean.

Make the frosting

While the cake bakes, prepare the frosting. In a saucepan, melt butter, cocoa powder, and milk together. Remove from heat and whisk in powdered sugar and vanilla until smooth.

Frost while warm

Pour the frosting over the warm cake and spread evenly. Sprinkle with nuts if desired. The frosting sets into a glossy, fudge-like layer.

Tips for the Best Sheet Cake