Moist Sponge Cake

This sponge cake has all the flavor and texture of genoise, but none of the dryness that genoise so often has. It is made just like a classic genoise, except that hot milk or cream and melted butter are folded into the beaten eggs at the same time as the flour, imparting extra moistness that makes it perfect for rolling. When baked in a 13 by 17-inch sheet pan, this moist cake is only about