Pour melted butter into a 9x13 baking dish. Sprinkl graham cracker crumbs over butter, stirring with a fork to cot well, then pressing into an even layer. Pour sweetened condensed milk over graham cracker crumbs. Refrigerate 15 minutes. Preheat oven to 350. Sprinkle coconut over sweetened condensed milk. Top with chocolate chips, then butterscotch chips, then walnuts. Bake 25 minutes or until lightly golden and set, but not browned.