Angel food cakes are made with egg whites alone and no yolks. The whites are whipped with sugar until very firm before the flour is gently folded in, resulting in a snowy-white, airy, and delicate cake that marries beautifully with fruit. Most angel food cakes have a spongy, chewy quality derived from their relatively high sugar content and the absence of egg yolks. Baked in ungreased two-piece tube pans, angel food cakes are cooled by being inverted, since this type of cake would collapse if cooled right-side-up in the pan or if removed from the pan while still warm. There's also no butter here, so the cake is fat free.