PREPARE brownie batter as directed on package for fudgy brownies; spread half onto bottom of 8-inch square pan sprayed with cooking spray.
ARRANGE cookies over batter in pan, overlapping as necessary to form single layer. Cover with remaining batter.
BAKE as directed on pan for fudgy brownies except add 3 min. to the suggested baking time. Cool completely.
MELT semi-sweet chocolate as directed on package; pour over brownie. Let stand until chocolate is firm before cutting brownie to serve.