Heat oven to 350 degrees F. (325 degrees F. for glass or dark non-stick pan). Coat a 13x9 inch baking pan with non-stick cooking spray or line with parchment.
In small bowl, combine graham cracker crumbs, sugar, and butter. Press into bottom of prepared pan. Mix sweetened condensed milk with vanilla. Pour sweetened condensed milk evenly over crumb mixture. Spread with an offset spatula to completely cover graham cracker crust. Empty chocolate chips and butterscotch chips into a bowl and mix together to combine (this step isn't necessary, but does ensure an equal distribution of chips). If desired, mix coconut and nuts together in the same way as chips to ensure an even distribution. Layer crust with chocolate chips and butterscotch chips; then layer with coconut and nuts. Press down lightly with a fork so that toppings partially sink into sweetened condensed milk.
Bake 25 minutes or until lightly browned. Very lightly press mixture with offset spatula to ensure toppings stay in place after cutting. Cool. Cut into bars.