Heat oven to 350F for shiny metal or glass 13x9 pan (or 325F for dark or nonstick 13x9 pan). Spray the bottom only of the pan with baking spray with flour.

Make the cake mix cake as directed on box, using water, oil, 1 1/2 tsp mint extract, and the egg whites. Reserve 1 cup batter; stir 3 drops of the green food coloring into the reserved batter and set aside. Pour the remaining batter into pan.

Drop green batter by generous tablespoonfuls randomly in 12-14 mounds onto the batter in pan. Cut through the batters with a metal spatula or knife in S-shaped curves in one continuous motion. Turn the pan 1/4 turn; repeat cutting for swirled design.

Bake 28-33 minutes or until a toothpick inserted in the center comes out clean. Run the knife around the side of the pan to loosen the cake.

Cool completely, about 1 hour.

Carefully spread the fudge topping evenly over the cake.

In a medium bowl, stir whipped topping, remaining 1/2 tsp extract, remaining 9 drops of green food coloring and the yellow food coloring until blended.

Spread whipped topping mixture evenly over fudge.

Garnish with candy pieces.

Store covered in refrigerator.