Fudgy Chocolate Layer Cake with Chocolate Frosting

This fudgy chocolate cake leans hard on cocoa: a full cup of unsweetened cocoa powder for two 9-inch layers, which is roughly double what most cake recipes use. The result is dense, moist, and unmistakably chocolate, the kind of crumb that holds together when sliced but melts when chewed.

The sugar split is the smart-baking move. Equal parts granulated and brown sugar gives you the structural lift of white sugar plus the molasses moisture that keeps the cake fudgy for days, not just hours. Buttermilk pulls double duty too. Its acid activates the baking soda for a clean rise, while its tang cuts the deep cocoa bitterness.

The frosting is a quick American buttercream stiffened with melted unsweetened chocolate, which keeps it firm at room temperature without needing to be refrigerated. Three ounces of melted chocolate adds depth that powdered-sugar-only frostings can’t touch.

Pro Tips

• Sift the cocoa powder before measuring. Cocoa clumps badly, and unsifted lumps will streak your batter.
• Use Dutch-process cocoa for a darker, smoother chocolate flavor. Natural cocoa works too but tastes brighter and more acidic.
• Don’t overmix once the dry and wet ingredients combine. Stop the moment everything is incorporated. Overmixing builds gluten and produces a tough cake.
• Cool the layers completely before frosting. A warm cake melts the buttercream and you’ll watch your frosting slide right off.

Variations

• Add a teaspoon of espresso powder to the batter. It deepens the chocolate without making the cake taste like coffee.
• Spread a thin layer of raspberry jam between the cake layers before frosting for a chocolate-raspberry version.
• Top with chocolate ganache instead of buttercream for a glossier, more bakery-style finish.