Basic French Sponge Cake

This is a purist’s cake because it contains no leavening—it’s lightened with air alone—and has a delicate egg flavor and a light texture that make it seem to fall apart in the mouth. To make this classic French sponge cake, you need to beat whole eggs with sugar until they become very pale and are tripled or quadrupled in volume. Because eggs whip up more quickly when they are not ice cold, warm them in a bowl of warm water before cracking them, or use a hand whisk to beat them with the sug