Lightly oil the sides and bottom of a 20 x 30cm (13”x9”) ceramic baking dish with canola oil.
Line the ceramic baking dish with parchment paper, covering the bottom and the sides. Set aside and prepare your other ingredients.
Per-heat the over at 170c (350f).
Double boil the butter until it’s all melted. Use low heat and be careful not to burn the butter.
Pour the butter into the ceramic baking dish. Sprinkle graham cracker crumbs over butter. It will soak up the hot butter and mix to become a solid foundation.
Build the cookie layers in this order; chocolate chips, coconut flakes, butterscotch chips, and walnuts.
Once all those ingredients have been added, press down gently to help the layers fuse together.
Pour sweetened condensed milk evenly over everything.
Cover with aluminum foil and bake for 25 minutes.
Rotate 180 degrees and bake for another 10 minutes.
Uncovered to and cook another 15 minutes to make it golden brown.
Let cool for 2 hours at room temperature before removing from the ceramic baking dish. Once it has cooled, cut into bars.