Preheat oven to 350℉. Spray a quarter sheet pan (or a 9x13 cake pan) with nonstick baking spray.
In a small mixing bowl, combine melted butter, graham cracker crumbs, sugar, and cinnamon. Stir util well combined. Press it into the pan, spreading it evenly.
Sprinkle the coconut evenly across the crust. Follow with the semisweet and white chocolate chips and nuts. Spread them out evenly so there's a little in every bite.
Drizzle condensed milk evenly over the bars. Tap the pan on the counter a few times to help the condensed milk seep into the bars. Then let them sit for a couple of minutes before baking.
Bake for 20-25 minutes, or until the white chocolate chips are beginning to brown on top, and the condensed milk is caramelized and bubbling.