HEAT oven to 350ºF. Prepare cake batter as directed on package. Remove 1 cup of the batter; pour into greased 2-cup ovenproof glass bowl. Pour remaining batter into greased foil-lined 13x9-inch baking dish. Bake both cakes for 25 to 30 min. or until toothpick inserted in centers comes out clean. Cool completely.
REMOVE 1/2 cup of the whipped topping; set aside. Stir food coloring into the remaining whipped topping. Invert 13x9-inch cake onto large serving platter. Remove pan. Frost cake with the green whipped topping.
INVERT round cake onto separate plate as shown in photo; spread with the white whipped topping. Place on top of 13x9-inch cake. Decorate with the black decorating gel as shown in photo to resemble a soccer ball. Store in refrigerator.