Preheat your oven to 350°F (175°C) and grease a 9x5 inch loaf pan.

In a large bowl, mash 3 ripe bananas until smooth, then stir in the granulated sugar, brown sugar, melted butter, eggs, and vanilla extract until well-blended.

Gently add baking soda, salt, and all-purpose flour to the banana mixture, combining carefully to avoid overmixing.

In a small bowl, combine granulated sugar with cinnamon to create your cinnamon sugar mixture.

Pour half of your banana bread batter into the prepared pan, sprinkle half of the cinnamon sugar over it, then add the remaining batter and finish with the rest of the cinnamon sugar.

Using a knife or skewer, gently swirl through the batter to create a marbled effect.

Bake in the preheated oven for 50-60 minutes, checking for doneness with a toothpick.

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

Prepare a glaze by mixing powdered sugar with a splash of milk until smooth.

Once cooled, drizzle the glaze over the top of the bread.