Preheat your oven to 350°F (175°C).
Grease your 9x13-inch baking dish with butter or cooking spray.
In a mixing bowl, combine the graham cracker crumbs and melted butter until evenly coated.
Press the graham cracker mixture evenly into the bottom of the prepared baking dish.
Pour the sugar-free condensed milk over the crust, then sprinkle chocolate chips, coconut flakes, and walnuts on top.
Bake in the preheated oven for 25-30 minutes until the edges are golden brown.
Let the bars cool completely in the pan before cutting into squares or bars.
