The Biscuit, on the other hand, is like an American Sponge in that it has no butter, but has more eggs. The egg yolks and whites are beaten separately. This produces a lighter, more delicate cake. In both the Genoise and Biscuit cornstarch has replaced some of the flour. This causes the grain of the cake to be tighter and enables the cake to hold more moisture.
Cake flour is used in sponge cakes which makes a sweeter, finer textured cake.
When making sponge cakes have all your ingredients pre-measured before starting. The assembly must be done quickly so that the eggs do not deflate after beating. Ingredients must be at their proper temperature in sponge cakes. Eggs are usually warmed to ensure their maximum volume when beating. The butter, if adding, is warmed to ensure it does not deflate the eggs.