1Make cookie dough as directed on package. Press dough into bottom of ungreased 13x9-inch pan. Bake at 375°F for 12 to 14 minutes. Cool.
2Mix powdered sugar, peanut butter and milk with electric mixer on medium speed until smooth. Stir in peanuts. Spread mixture over cookie crust.
3In 1-quart saucepan, heat chocolate chips and butter over low heat, stirring frequently until melted and smooth. Remove from heat; stir in whipping cream until blended. Spread evenly over peanut butter mixture. Top with sprinkles. Refrigerate 1 hour or until set.