Preheat the oven to 350℉. Line two 12-count muffin tins with parchment paper liners or spray with non-stick cooking spray or grease with butter.

In a large mixing bowl, whisk together the melted butter, sugar, eggs, and vanilla. Stir in the mashed banana, drained pineapple, and coconut.

In another bowl, whisk together the flour, baking soda, and baking powder. Add to the bowl of wet ingredients and stir just until incorporated and no streaks of flour remain, being careful not to overmix.

Evenly distribute the batter between the prepared pans, filling each cup or liner to the top with batter. In a small, bowl stir together the crumble ingredients: melted butter, sugar, flour, and chopped macadamia nuts to make a crumbly mixture. Top the unbaked muffins with the crumble topping, evenly distributing the topping between all the muffins.

Bake in the preheated oven for 20-25 minutes or until a toothpick inserted into the center comes out clean. Let the muffins cool in the pans for 10 minutes before transferring to a wire rack to finish cooling before topping with the icing.

Stir together 2-3 tablespoons of coconut milk and the powdered sugar to create a drizzle-able icing/glaze. Drizzle over the mostly cooled muffins and serve. Enjoy!