Classic American Butter Cake

This cake shares certain characteristics with pound cake-butter is beaten with sugar—but is leavened by separating the eggs and beating the whites and by using a small amount of baking powder. It is a great standby white cake with plenty of buttery flavor. Egg whites are ideally beaten in a copper bowl (copper chemically interacts with the protein in egg whites to create a particularly stable, satiny high-volume foam). If you don’t have such exotic accessories, just add