In a medium bowl, mix together the butter or margarine, graham cracker crumbs, confectioners' sugar, and 1 cup peanut butter until well blended. Press evenly into the bottom of an ungreased 9x13 inch pan.
In a metal bowl over simmering water, or int he microwave, melt the chocolate chips with the peanut butter, stirring occasionally until smooth. Spread over the prepared crust. Refrigerate for at least one hour before cutting into squares.
NOTE: After putting in the refrigerator for 30 minutes to an hour, I cut through the top chocolate layer. Then when it is fully cooled, I cut into squares.