Preheat oven to 350 degrees. Line a 9x13 pan with parchment paper and spray with cooking spray.
In a bowl mix the melted butter and graham cracker crumbs. Once mixed press into 9x13 pan.
Sprinkle chocolate chips over crumb crust (you need 2 c. total of chips, but you can use any kind and combination you'd like).
Sprinkle coconut on top of chips. Add nuts here if you're using them.
Pour can of sweetened condensed milk evenly over ingredients in pan. Make sure it's all covered. Pouring this on last keeps the coconut from burning.
Bake for 23-25 minutes until sides are golden brown and starting to pull away from pan. Slice into squares and enjoy the magic.