Preheat oven to 400˚. Grease a 12-cup muffin tin or line with paper cups.
In a large mixing bowl, stir together the flour, coconut, sugar, baking powder, and salt. In a separate mixing bowl, whisk together the crushed pineapple, coconut milk, eggs, and melted butter.
Fold the wet mixture into the flour mixture, stirring just until moistened. Fill the muffin cups 3/4 full. Bake 20-25 minutes, until golden brown.
In a small bowl, stir together the powdered sugar and reserved pineapple juice. Brush this pineapple glaze on the hot muffins. Allow the muffins to cool in the tins for 5 minutes, then transfer to a wire rack to finish cooling.