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 x 13 inch pan.

In a metal bowl over simmering water, or in the microwave, melt the chocolate chips with the peanut (4 tbsp), stirring occasionally until smooth.

Spread over the peanut butter layer.

Refrigerate for at least 1 hour before cutting into squares.