Triple Chocolate Cake

This recipe is from Taste of Home Magazine.

1 package (18-1/4 ounces) white cake mix
1/3 cup sugar
4 eggs
1 cup (8 ounces) sour cream
2/3 cup canola oil
2 tablespoons baking cocoa
1/2 cup miniature semisweet chocolate chips
1 cup chocolate frosting
2 tablespoons milk
Directions:
In a large bowl, combine the cake mix, sugar, eggs, sour cream and oil. Beat on low for 1 minute; beat on medium for 2 minutes. Pour half of the batter into a large bowl. Stir in cocoa until blended. Fold chocolate chips into white cake batter.
Alternately spoon batters into a greased and floured 10-in. fluted tube pan. Bake at 350° for 45-50 minutes or until a toothpick inserted near the center comes out clean. Cool for 15 minutes before removing from pan to a wire rack to cool completely.
In a small bowl, combine frosting and milk. Spoon over top of cooled cake. Yield: 12 servings.