Preheat your oven to 350°F (175°C) and grease a standard loaf pan with butter or non-stick spray.

Mash the ripe bananas in a large mixing bowl until mostly smooth and creamy.

Combine the mashed bananas with granulated sugar, brown sugar, melted butter, and an egg, mixing until thoroughly combined.

In a separate bowl, whisk together all-purpose flour, baking soda, and cinnamon, then fold into the banana mixture.

Prepare the crumb topping by mixing brown sugar, flour, cinnamon, and melted butter until it resembles coarse crumbs.

Pour the banana batter into the greased loaf pan and sprinkle the crumb topping evenly on top.

Bake for 60-65 minutes until a toothpick inserted comes out clean or with a few moist crumbs.

Cool in pan for 10 minutes, then transfer to a wire rack to cool completely.