Combine melted butter, finely ground graham cracker crumbs, confectioners' sugar and 1 cup peanut butter. Spread in a 9x13 inch pan.
In the microwave or over the stove, melt 4 tablespoons peanut butter and chocolate chips until smooth. If melting In the microwave stir after every 30 seconds to make sure that it doesn't burn. Spread on top of the peanut butter layer.
Refrigerate for at least an hour before serving so that they can set. Store leftover bars in the fridge.