This marble angel food cake recipe is perfect for those who want a lighter and fluffier cake. It's made with egg whites, sugar, flour, and cream of tartar. To make the cake, start by beating egg whites and cream of tartar together until stiff peaks form. Then gradually add sugar and continue beating until the mixture is glossy. In a separate bowl, sift together flour and salt. Fold the dry ingredients into the egg white mixture, being careful not to overmix. Finally, divide the batter in half and mix cocoa powder into one half. Pour the vanilla and chocolate batter into an ungreased angel food cake pan, alternating between the two. Use a knife to swirl the batter together to create a marble effect. Bake for 35-40 minutes at 350°F. Let the cake cool before removing it from the pan and serving.
