Prep: 15 minutes; Cook: 25 minutes; Total time: 40 minutes.
Preheat oven to 375°. Place paper liners in a 12-cup muffin pan.
Whisk dry ingredients (through salt) in a large bowl. Whisk bananas, egg, egg white, oil, vanilla, and coconut milk in another large bowl until well combined.
Stir together wet and dry ingredients until just combined. Gently fold in 1/4 cup of the coconut.
Transfer the batter to the prepared pan. Top with the remaining coconut.
Bake until golden brown and a skewer inserted in center of a muffin comes out clean (about 25 minutes). Transfer to a wire rack and cool slightly.
Note: If you want to make a loaf, spread batter into a 9- x 5-inch loaf pan lightly coated with baking spray and flour. Bake until golden brown and a skewer inserted in the center comes out clean (50 to 55 minutes). Cool in the pan for 10 minutes, then place on a wire rack and let cool.