Preheat the oven to 350°F (175°C) and grease or line a 9×5-inch loaf pan.
Mash the ripe bananas in a large bowl.
Stir in the melted butter, sugar, eggs, and vanilla extract.
In a separate bowl, whisk together the flour, baking soda, salt, cinnamon, and nutmeg.
Add the dry ingredients to the wet ingredients and gently stir until just combined.
Pour the batter into the prepared loaf pan.
Mix the topping sugar and cinnamon together and sprinkle over the batter.
Bake for 50–60 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs.
Cool in the pan for 10–15 minutes, then transfer to a wire rack.
Allow to cool before slicing and serving.