Heat oven to 350 degrees. Coat 13x9-inch baking pan with no-stick cooking spray.
Melt butter in baking pan. Sprinkle graham cracker crumbs over that. Pour sweetened condensed milk evenly over crumb mixture. Layer evenly with chocolate chips, coconut and nuts. Press down firmly with a fork.
Bake 6-8 minutes. Cool. Cut into bars. I like to refrigerate them, and eat them that way. Serve, and watch them vanish :)
I have never made them with nuts, I like them without. You can substitute other kinds of chips with 1/2 choc. chips and 1/2 other kind- butterscotch, peanut butter, etc. But I like the full chocolate :)