PLACE cake on serving plate. Cut 3/4-inch-thick horizontal slice from top of cake using a serrated knife; set aside. With small knife, cut 1-inch wide and 1-inch deep tunnel inside center of cake; being careful not to cut through. Remove and save cutout for snack.
STIR boiling water into 1 pkg. (4-serving size) dry Jell-O Brand Gelatin in bowl 2 min. until dissolved. Add enough cold water to 1/2 cup ice to measure 3/4 cup; stir into gelatin until completely melted. Remove 1/2 cup of the gelatin mixture and place in separate medium bowl. Add whipped topping; stir with wire whisk until well blended. Refrigerate 10 to 15 min. or until thick enough to spread.
MEANWHILE, refrigerate remaining plain gelatin 5 to 10 min. or until thickened. Stir in 3/4 cup of the fruit; spoon into tunnel of cake. Replace top of cake. Frost cake with reserved thickened whipped topping and gelatin mixture. Garnish top with remaining fruit.