Combine the butter or margarine, graham cracker crumbs, confectioners’ sugar, and 1 cup peanut butter in a medium mixing bowl until well combined. Press evenly onto the bottom of a 9×13 inch pan that hasn’t been oiled.
Melt the chocolate chips with the peanut butter in a metal bowl over simmering water or in the microwave, stirring regularly until smooth. Cover the prepared crust with the mixture. Before cutting into squares, chill for at least one hour.