1. Preheat oven to 350 degrees F. Spray 9" by 13" pan with cooking spray. Crush package of Oreo Cookies into crumbs, and mix with 1/3 cup melted margarine. Spread evenly in bottom of pan. Bake for 10 minutes. Cool.
2. Mix together well cream cheese, confectioners' sugar, 8 oz. Cool Whip and peanut butter, and spread over cooled crust.
3. Mix pudding mix with milk, and spread over peanut butter mixture.
4. When pudding has fully set, top with 8 oz. Cool Whip.