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

In a large mixing bowl, peel and thoroughly mash 3 to 4 ripe bananas using a fork or potato masher until smooth.

Add granulated sugar, brown sugar, melted butter, and one beaten egg into the bowl with the mashed bananas. Stir until smooth.

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

In another bowl, prepare the crumb topping by mixing brown sugar, flour, ground cinnamon, and melted butter until coarse crumbs form.

Pour the banana batter into the greased loaf pan, smoothing the top, and sprinkle the crumb topping evenly over it.

Place the loaf pan in the preheated oven and bake for 60 to 65 minutes, or until a toothpick comes out clean.

Once baked, cool the loaf in the pan for about 10 minutes before transferring it to a wire rack to cool completely.

Slice the cooled bread into thick pieces and serve warm or at room temperature.