pour the butter into a baking sheet. sprinkle graham cracker crumbs in an even layer over top, followed by the coconut, the chocolate chips and the walnuts.
evenly drizzle the sweetened condensed milk over top, making sure to reach the edges. bake at 350 for 15 minutes, then turn the temperature down to 325 and bake an additional 10-15 minutes or until golden brown and bubbling.
let cool. before completely set, cut into squares and refrigerate.