Combine the butter, graham cracker crumbs, confectioners' sugar, and 1 cup peanut butter in a large mixing bowl until well blended. Press evenly into the bottom of an ungreased 9x13 inch pan. Meanwhile, put chocolate chips and peanut butter into a microwave safe bowl. Microwave in 10-second increments until melted. Stir until smooth.  Pour chocolate mixture over crust. Chill for at least 3 hours.