Your sense of touch will tell you when the vanilla seeds are thoroughly mixed into the sugar. Also, you'll know the cake has finished baking when you press the surface and it springs back. Serve with fresh berries or fat-free whipped topping, if desired.Angel food cake is guilt-free with almost no fat, cholesterol or sodium. Egg whites, which gives the cake its white color, have little to no fat compared with egg yolks. Serve with berries for even more flavor and a boost of antioxidants.