Preheat oven to 450. Lightly crumple some aluminum foil and place it on a large baking sheet. Set aside. In a shallow bowl or on a plate, combine the chopped macadamia nuts and the coconut. Set aside. Rinse the shrimp. In a large Ziploc bag, combine the flour, lime zest, kosher salt, cayenne, garlic, and onion powder. Add the shrimp and toss to coat. Shake the excess flour from the shrimp. If your shrimp are smaller, dip a few shrimp at a time in the egg mixture, shake off the excess, and then roll them in the coconut/macadamia mixture. Place on the prepared baking sheet. If your shrimp are large, work with one at a time. Repeat with remaining shrimp. Place the baking sheet in the pre-heated oven. Bake for 10 minutes (slightly longer if your shrimp are very large).