Chocolate Butter Cake
Preheat the oven to 350 degrees. Brush the cake pans with butter. Line each with parchment paper; butter the parchment, and dust with flour, tapping out any excess; set aside.Advertisement
Sift together the flour, cocoa powder, baking powder, and salt into a medium bowl; set aside. Stir together the milk and vanilla; set aside. Beat the butter on medium speed in a mixer bowl until pale and fluffy, about 3 minutes. Add the sugar in a steady stream; mix until pale and fluffy, about 3 minutes.
Reduce the speed to low. Add the flour mixture in three batches, alternating with the milk mixture and beginning and ending with the flour; mix until just combined.
In a clean mixer bowl, whisk the egg whites just until stiff peaks form. Fold the egg whites into the batter in three batches. Divide the batter among the prepared pans; smooth tops with an offset spatula. Firmly tap the pans on a work surface to release air bubbles.
Bake until a cake tester inserted into the centers comes out clean and the tops are springy to the touch. Let cool in the pans on wire racks for 15 minutes; turn out onto racks to cool completely, top sides up.
Approximate batter amounts and baking times for 3-inch-deep round pans: 6-inch: 3 cups, 30 minutes; 8-inch: 5 cups, 40 minutes; 10-inch: 8 cups, 1 hour 5 minutes; 12-inch: 11 cups, 1 hour 15 minutes.