Bake white cake in 2 round layer pans. Remove layers from pans and cool, then put layers back in clean pans; prick with fork all over.

Pour 1 cup boiling water over 3 ounce package of Jello (any color, use 1 package red and 1 package green for Christmas). Pour Jello over 1 layer of cake; repeat for 2nd layer. Cool in refrigerator until Jello is hardened. Loosen from pans by setting in warm water for a minute. Frost with whipped topping. Store in refrigerator.