Coat a 13x9-inch baking dish with cooking spray. Tear angel food cake into bite-size pieces.
In a large bowl, prepare pudding mix with 1 ½ cups skim milk. Whisk until it starts to become creamy.
Fold both containers of cool whip into pudding mixture.
In prepared baking dish, layer half of the cake, half pudding mixture and half of the crushed Butterfingers. Repeat layers.
Refrigerate at least an hour before serving.