Preheat your oven to 350°F (175°C). Grease a 9x5 inch loaf pan.
In a mixing bowl, combine the mashed bananas with the melted butter, stirring until well blended.
Add the baking soda and salt to the banana mixture, and mix well.
Stir in the sugar, beaten egg, and vanilla extract until combined.
Gradually fold in the flour until just incorporated; do not overmix.
In a small bowl, mix the cinnamon and brown sugar together for the swirl.
Pour half of the banana bread batter into the prepared loaf pan, then sprinkle half of the cinnamon sugar mixture on top.
Add the remaining batter and top with the remaining cinnamon sugar mix, swirling it gently with a knife to create a ribbon effect.
Bake for 60-65 minutes, or until a toothpick inserted into the center comes out clean.
Allow the bread to cool in the pan for 10 minutes before transferring to a wire rack to cool completely.
Notes
Slice the banana bread and serve with a light dusting of extra cinnamon sugar or a dollop of cream cheese spread for added richness. A small sprig of mint on the side makes for a lovely garnish.