Preheat the oven to 350°F (175°C) and grease a 9-inch loaf pan.

In a large bowl, combine melted butter, brown sugar, and granulated sugar until smooth. Whisk in sour cream and eggs one at a time.

Mash the ripe bananas in the bowl and mix them into the wet ingredients.

Add flour, baking soda, baking powder, salt, and cinnamon, folding gently.

Pour batter into the prepared loaf pan and bake for 45-55 minutes, or until a toothpick comes out with moist crumbs.

Cool the bread in the pan for 10-15 minutes, then transfer to a wire rack to cool completely.