HEAT oven to 350ºF.
PREPARE cake batters, in separate bowls, as directed on packages. Stir cookies into chocolate cake batter.
SPRAY 10-inch tube pan with cooking spray. Pour half the chocolate batter into prepared pan. Cover with white batter, then remaining chocolate batter.
BAKE 1 hour 10 min. or until toothpick inserted near center comes out clean. Cool cake in pan 10 min. Loosen from sides of pan with knife. Invert cake onto wire rack; gently remove pan. Cool cake completely. Sprinkle with sugar.