In a medium bowl, mix together the melted butter, graham cracker crumbs, confectioners’ sugar, and 1 cup peanut butter until well blended. Press evenly into the bottom of an ungreased 9×13 inch pan. (I did mine in a 9X9 square pan because I wanted them thicker) In the microwave, melt the chocolate chips with the peanut butter, stirring every 30 seconds until melted until smooth. Spread over the peanut butter layer. Refrigerate for at least one hour before cutting into squares.