By definition, a sponge cake is a light. airy tender cake of the foam variety meaning the egg whites are beaten separately and the egg yolk base is folded into the whites along with flour. It can be varied easily and is used as a base for many fillings. The name comes from its open structure which resembles a sponge. The plain sponge cake on its own is rather neutral and doesn’t have a lot of flavor which is why recipes often brush the sponge cake layers with liqueur based washes.. However, by enhancing it with lemon zest and adding a little butter it becomes a more flavorful vehicle for fillings. By omitting the zest, you have a basic Butter Sponge Cake. By omitting the butter, you have a basic Sponge Cake.
Another characteristic of the sponge is that it doesn’t contain shortening except in the Butter Sponge Cakes. Sponge cakes can be dry if the egg whites are over beaten. It is better to under beat them than get them too stiff. When the whites are too stiff, it is difficult to fold the flour in without deflating the whites. Continue reading