PREHEAT oven to 350ºF. Prepare cake batter as directed on package; set batter aside. Spray 13x9-inch baking dish generously with cooking spray. Sprinkle dry jelly powder onto bottom of dish. Top with pineapple rings; place cherry in centre of each ring.
POUR batter evenly over fruit in dish.
BAKE 30 min. or until wooden toothpick inserted in centre comes out clean. Cool in dish on wire rack 5 min. Loosen cake from sides of dish. Invert onto serving platter; gently remove dish. Cool completely. Serve topped with the whipped topping.