Preheat your oven to 350°F (175°C) and prepare a 9-inch bread pan by greasing it or lining it with parchment paper.

In a large mixing bowl, combine melted butter, brown sugar, and white sugar until smooth and creamy.

Whisk in sour cream until combined, then add eggs one at a time, whisking thoroughly after each addition.

Mash the ripe bananas in a separate bowl and fold them into the wet mixture.

In another bowl, whisk together flour, baking soda, baking powder, salt, and ground cinnamon.

Gradually add the dry mixture to the wet ingredients, stirring gently until just combined.

Pour the batter into the prepared bread pan, smoothing the top.

Bake for 45 to 55 minutes, checking for doneness with a toothpick starting at 35 minutes.

Let the bread cool in the pan for about 15 minutes, then transfer to a wire rack.