1. Heat oven to 350 degrees F. Line a 13-by-9-by-2-inch baking pan with foil, extending foil over pan's edges. Put butter in the pan and place in oven for about 5 minutes, or until butter melts. Tilt pan to coat evenly. Sprinkle with crushed graham crackers; layer with walnuts, chocolate chips and coconut. Drizzle with sweetened condensed milk.
2. Bake for 20 to 25 minutes, or until edges are lightly browned. Cool in pan on a wire rack for 15 minutes. Use foil to lift from pan and then cut into bars. Let cool completely.