In a bowl, combine 1/2 cup melted butter and graham cracker crumbs. Press firmly and evenly into a 13" x 9" glass baking pan.
Evenly sprinkle the coconut over the graham layer.
Evenly pour the sweetened condensed milk over the cocnut layer.
Bake at 325 for 25 minutes or until just lightly browned; remove from oven.
While base is in oven, in a microwave-safe bowl, or a small saucepan, melt the chocolate chips and peanut butter together, stirring often until smooth. Pour this mixture over baked base. Allow to cool/set for at least 4 hours before cutting.