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

In a mixing bowl, mash 2-3 ripe bananas until smooth and stir in the melted butter, granulated and brown sugars, eggs, and vanilla extract until well combined.

In a separate bowl, whisk together the all-purpose flour, baking soda, baking powder, salt, and cinnamon.

Gradually fold the dry ingredients into the wet mixture until just combined, being careful not to overmix.

Pour half of the batter into the loaf pan, sprinkle a layer of cinnamon-sugar mixture, add remaining batter, and create a swirl with a knife.

Bake for 50-60 minutes, checking with a toothpick for doneness. It should come out clean or with a few crumbs.

Let the bread cool in the pan for 10 minutes, then transfer to a wire rack. Mix powdered sugar and milk for glaze and drizzle over the warm bread.

Slice and serve warm for breakfast or as a snack.