Bake cake as directed on box in a 13 x 9 pan. Leave cake in this pan. As soon as it comes out of the oven, poke holes in top of cake with a fork. Pour caramel over top of cake. Set aside cake to cool.
Mix Cool Whip, Marshmallow Creme, and Sweetened Condensed Milk together until blended. Frost top of cake.
Crush Butterfinger in zip lock bag. Sprinkle on top of frosting.
Not a NESTLÉ®-tested recipe.