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 the can 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.
