Beat pudding mix and milk in large bowl with whisk 2 minutes. Let stand 5 minutes.

Cover bottom of an 8-inch square pan with graham pieces, overlapping as needed to form an even layer

Stir Cool Whip into the pudding. Spread half over the graham pieces in the pan. Cover with 10 of the remaining graham pieces. Repeat layers of pudding mixture and graham pieces.

Refrigerate 3 hours. Spread with chocolate frosting. Serve.