Sponge cake is a cake based on flour (usually wheat flour), sugar, and eggs, and is sometimes leavened with baking powder. It has a firm, yet well aerated structure, similar to a sea sponge. A sponge cake may be produced by the batter method or the foam method.Cake made using the batter method is known as a butter or pound cake in the U.S., while in the U.K. it is known as Madeira cake or Victoria sponge cake.