HEAT oven to 350ºF.
PREPARE brownie batter as directed on package; spread onto bottom of 12-inch pizza pan sprayed with cooking spray. Bake 15 min. or until toothpick inserted in centre comes out with fudgy crumbs. (Do not overbake.) Cool 30 min.
ADD food colourings to Cool Whip; stir gently until blended. Spread over brownie;
TOP with remaining ingredients.
serving size = 1 piece (50 g)