Preheat your oven to 350°F (175°C) and grease a 9x5-inch loaf pan.
In a mixing bowl, combine the mashed bananas and melted butter until well blended.
Stir in the baking soda and salt.
Add the sugar, beaten egg, and vanilla extract, mixing until smooth.
Gradually fold in the flour until just combined. Be careful not to overmix.
In a small bowl, mix the chocolate chips, ground cinnamon, and brown sugar.
Pour half of the banana bread batter into the prepared loaf pan. Sprinkle half of the chocolate chip mixture over the batter.
Add the remaining batter on top and then sprinkle the rest of the chocolate chip mixture. Use a knife to swirl the chocolate chips into the batter gently.
Bake in the preheated oven 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 it to a wire rack to cool completely.