Double Chocolate Marble Cake

Directions

1. 1
   Preheat oven to 325 degrees F (165 degrees C). Grease an flour one 10 inch tube pan.
2. 2
   To make marbling mixture: Combine 1/3 cup of the coca and 1/2 cup of the white sugar and mix well.
3. 3
   In a large bowl, beat the egg whites until stiff, and set aside.
4. 4
   In another bowl, cream the butter with 1 cup of the sugar and the brown sugar. Beat in the egg yolks, then the vanilla and sour cream.
5. 5
   In another bowl, stir together the flour, cocoa, salt, and baking soda. Beat into the creamed mixture. Stir about 1/3 of the egg whites into the batter to lighten it and then fold in the rest gently but thoroughly. Spread about 1/4 of the batter into a greased and floured tube pan and sprinkle with about 1/3 of the cocoa-sugar mixture. Continue repeating layers, ending with the batter. With a knife, lightly swirl the batter and cocoa mixture together
6. 6
   Bake at 325 degrees F (175 degrees C) for 1 3/4 hours, or until it tests done with a toothpick. Let cool on a rack. Makes 16 to 20 servings.