Preheat your oven to 410°F (210°C) and line a standard 12-cup muffin tin with paper liners or grease each cup lightly.
In a large mixing bowl, combine the mashed bananas, melted butter, lightly beaten eggs, granulated sugar, and vanilla extract. Stir until the mixture is well combined.
In a separate bowl, whisk together the bread flour, baking powder, baking soda, ground cinnamon, and salt.
Gradually add the dry ingredients to the banana mixture, stirring until just combined. Be careful not to overmix; it's okay if there are a few lumps.
Gently fold in the cubed banana, chopped candied walnuts, and shredded coconut into the batter.
Divide the muffin batter equally among the 12 prepared muffin cups, filling each about 2/3 or more full.
In a small bowl, mix together the ½ cup of chopped candied walnuts and 2 tablespoons of granulated sugar for the topping.
Sprinkle the walnut-sugar mixture evenly over the top of each muffin.
Place the muffin tin in the preheated oven and bake for 15-18 minutes, or until a toothpick inserted into the center of a muffin comes out clean and the tops are golden brown.
Once done, remove the muffins from the oven and allow them to cool in the muffin tin for about 5 minutes.
After cooling slightly, transfer the muffins to a wire rack to cool completely.