Melt the butter or margarine in a 9x13 inch baking pan. Sprinkle the graham cracker crumbs evenly over the butter. Sprinkle on the chocolate chips and butterscotch chips. Cover with the flaked coconut. Sprinkle the walnuts on top of the coconut layer. Finally, pour the condensed milk over everything as evenly as you can.
Bake for 30 to 35 minutes in the preheated oven. Cool, and cut into bars.