Preheat oven to 350 degrees. Grease and flour three 9 inch round cake pans.
In a large bowl, combine white cake mix, egg whites, buttermilk and vegetable oil. Mix with an electric mixer for 2 minutes on high speed.
In a separate bowl, combine yellow cake mix, buttermilk, egg, cocoa, red food coloring and vinegar. Use an electric mixer to beat for 2 minutes on high speed.
Spoon white batter alternately with red batter into the prepared cake pans. Swirl batter gently with a knife to create a marbled effect.
Bake for 22-25 minutes, or until a wooden pick inserted into the centers comes out clean. Let cool in pans for at least 10 minutes before turning out onto a wire rack to cool completely.
In a large bowl, beat cream cheese and margarine until smooth. Gradually blend in sugar until incorporated and smooth. Stir in peppermint extract. Spread peppermint cream cheese frosting between layers, and on top and sides of cake.