CRUSH 8 of the cookies in resealable plastic bag with rolling pin. Mix cookie crumbs and butter. Press onto bottom of foil-lined 9x5-inch loaf pan.
MIX cream cheese, peanut butter, sugar and vanilla with electric mixer on medium speed until well blended. Gently stir in 3 cups of the whipped topping. Spoon ½ cup of the cream cheese mixture into small bowl. Stir in melted chocolate until well blended; set aside. Spoon half of the remaining cream cheese mixture over crust. Top evenly with chocolate mixture; cover with remaining cream cheese mixture.
FREEZE 4 hours or overnight until firm. Invert onto plate. Remove foil, then re-invert onto serving platter so that crumb layer is on bottom. Coarsely break the remaining 4 cookies. Top dessert with remaining whipping topping and cookies.