Preheat oven to 400 degrees F. To prepare muffins, lightly spoon flour into dry measuring cups; level with a knife. Combine flour and next 4 ingredients (through salt) in a large bowl. Make a well in center of flour mixture. Combine banana and next 5 ingredients (through egg) in a medium bowl; add to flour mixture, stirring just until moist. Stir in pineapple, 1/3 cup coconut, and 3 tablespoons nuts. Spoon batter into 12 muffin cups coated with cooking spray.
To prepare topping, combine 2 tablespoons coconut and the remaining ingredients in a small bowl. Sprinkle about 1 teaspoon of topping over each muffin.
Bake for 18 minutes of until muffins spring back when touched lightly in center. Remove muffins from pans immediately; place on a wire rack.