Creating this Cinnamon Swirl Banana Bread is straightforward when you follow these steps:

1. Preheat your oven to 350°F (175°C). Grease and flour a 9×5-inch loaf pan.
2. Mash the bananas in a large mixing bowl until smooth, leaving a few small lumps for texture.
3. Mix in the melted butter until incorporated.
4. Stir in the baking soda and salt. Allow it to rest for 5 minutes.
5. Add the sugar and mix well.
6. Incorporate the beaten egg and vanilla extract, stirring until combined.
7. Gently add the flour and mix until just combined. Do not overmix.
8. In a separate bowl, combine the brown sugar and ground cinnamon. This will be used for the swirl.
9. Layer the batter: Pour half of the banana batter into the prepared loaf pan. Sprinkle half of the cinnamon sugar mixture over it.
10. Repeat with the remaining banana batter and cinnamon sugar.
11. Use a knife to swirl through the batter gently, creating a beautiful marble effect.
12. Bake for 50-60 minutes, or until a toothpick inserted comes out clean.
13. Allow cooling in the pan for about 10 minutes, then transfer to a wire rack to cool completely.

These steps will guide you in creating this delicious Cinnamon Swirl Banana Bread effortlessly.