LINE 13x9-inch pan with foil, with ends of foil extending over sides. Crush 20 cookies; sprinkle crumbs onto bottom of prepared pan.
SPREAD ice cream evenly over crumbs in pan; top with COOL WHIP and grated chocolate.
FREEZE 3 hours. Remove from freezer 15 minute before serving. Let stand at room temperature to soften slightly. Lift dessert from pan with foil handles; cut into 16 squares. Cut remaining cookies in half; place 1 on each square.