In a small bowl, combine cookie crumbs and sugar if desired. Stir in butter. Press onto the bottom and up the sides of an ungreased 9-in. pie plate. Refrigerate for 30 minutes. , Spoon 2 cups ice cream into crust. Drizzle with half of the chocolate syrup; swirl with a knife. Gently top with remaining ice cream. Drizzle with remaining syrup; swirl with a knife. Freeze until firm. , Remove from the freezer 10-15 minutes before serving. If desired, top with whole cookies.