Simple Chocolate Sheet Cake

From America's Test Kitchen Season 4: Easy Sheet Cakes

Sheet cakes, for all their simplicity, can still turn out dry, sticky, or flavorless and, on occasion, can even sink in the middle. We wanted to find a simple, dependable recipe, one that delivered a moist yet also tender and chocolaty cake.

We started with the mixing method—testing everything from creaming butter to beating yolks, whipping whites, and gently folding together everything in the end. The best of the lot was the most complicated to make, so we took a step back. The simplest technique we tried was simply whisking all the ingredients together without beating, creaming, or whipping. The recipe needed work, but the approach was clearly a good match for the simple all-purpose nature of a sheet cake. First we added buttermilk and baking soda to lighten the batter, since the original cake had been too dense. To increase the chocolate flavor, we reduced the sugar and flour, and decreased the butter. To further deepen the chocolate taste, we used semisweet chocolate in addition to the cocoa. We baked the cake at a low temperature for a long time—40 minutes—to produce a perfectly baked cake with a lovely flat top. Though this cake can be frosted with almost anything, we like a classic American milk chocolate frosting, which pairs well with the darker flavor of the cake.