1. Fold 1-1/2 cups whipped topping into fruit cocktail just until blended. Split cake horizontally into three layers; place one layer on a serving plate. Spread with half of the fruit mixture. Repeat layers. Top with remaining cake layer.
2. Frost top and sides with remaining whipped topping. Arrange mandarin oranges on top. Refrigerate until serving. Serve with orange slices and mint if desired. Yield: 12 servings.