Melt butter in a saucepan or microwave; pour into a 9x13-inch baking dish, tilting to coat. Sprinkle on the graham cracker crumbs; press mixture with your hands to form a crust.
Layer the chocolate chips, butterscotch chips, coconut, and peanuts over the graham cracker crust. Pour the condensed milk over the layers.
Bake in preheated oven until edges begin to brown, about 20 minutes. Allow to cool before cutting into bars.