Stir in 3 cups of the whipped topping and 1/2 of the cookies. Spoon into 13 x 9-inch baking dish. Sprinkle with remaining cookies, Refrigerate 1 hour or until ready to serve. Store dessert in refrigerator.
Decorate with cookies (tombstones [these appear to be Pepperidge Farm Milano cookies), candy and remaining whipped topping dropped by spoonfuls (ghosts).