Line a square pan with parchment paper, making sure to leave enough paper on the edges to be able to lift out of pan when done.
Pour graham cracker crumbs and butter into prepared pan and combine together. Then press the mixture down to form crust.
Sprinkle and layer next three ingredients on top. First pour chocolate chips into even layer. Then sprinkle walnuts on top in even layer. Finally add coconut flakes in a thick even layer. Slowly pour the sweetened condensed milk evenly on top so that the coconut flakes are all covered.
Bake until lightly brown on top, about 25 to 30 minutes. Make sure there are no puddles of visible condensed milk on top. Remove from oven and transfer to a wire rack. Cool for at least 20 minutes before cutting to preferred bar size/shape.