HEAT oven to 350°F.
CRUSH 16 cookies; coarsely chop remaining cookies. Mix crushed cookies with butter; press onto bottom of 9-inch square pan sprayed with cooking spray.
SPREAD marshmallow creme onto crust to within 1/2 inch of edges; top with chopped chocolate, nuts and chopped cookies. Press lightly into marshmallow creme to secure.
BAKE 18 to 20 min. or until lightly browned; cool completely before cutting into bars.
serving size = 1 bar (38 g)