Preheat the oven to 325 degrees F (165 degrees C).

Mix graham cracker crumbs and melted butter together in a bowl until evenly moistened; press into the bottom of a 9x13-inch baking dish.

Pour 1/2 of the can of sweetened condensed milk over the graham cracker crust. Sprinkle semisweet chocolate chips, walnuts, coconut, and white chocolate chips over the graham cracker crust; gently press chocolate, nuts, and coconuts into the crust. Drizzle remaining 1/2 can of condensed milk over the top.

Bake in the preheated oven until fragrant and coconut is golden, 25 to 30 minutes. Cool completely before cutting into squares.