Preheat your oven to 350 degrees. Melt butter in microwave-safe bowl and add the graham cracker crumbs to it. Stir to combine and press crumb mixture into a parchment paper lined and greased 9 x 13 baking pan.
Pour the sweetened condensed milk evenly over the crumb mixture.
Layer evenly with half of the chocolate, butterscotch, white chocolate and peanut butter chips, then top with half the amount of coconut (about 3/4 cup). Then, sprinkle on the remaining chips and rest of the coconut. Sprinkle on the toffee bits over the top. If using, sprinkle on the mini marshmallows over the top.
Bake at for about 25 to 30 minutes, or until the top is barely browning. Let cool, slice and serve!