Coarsely chop 15 of the cookies; set aside. Finely crush remaining cookies; mix with butter. Press firmly onto bottom of 13x9-inch pan. Refrigerate while preparing filling. Beat cream cheese, sugar and vanilla in large bowl with electric mixer on medium speed until well blended. Gently stir in whipped topping and chopped cookies. Spoon over crust; cover. Refrigerate 4 hours or until firm. Store leftovers in refrigerator.