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 9×13 inch pan.
Put cream and chocolate chips into a kettle, boil up and stir until smooth. Spread over the prepared crust. Refrigerate for at least one hour before cutting into squares.