Mix bananas, butter, sugar, egg, and vanilla together. Add baking soda and salt on top of the banana mixture. Then gently stir in flour. Do not over-mix.
In a small dish, mix together the ¼ cup sugar and 3 teaspoons cinnamon.
Add ½ of the batter to the loaf pan and then sprinkle more than half of the cinnamon-sugar mixture all over the batter in the pan. Add the rest of the batter, and then sprinkle the leftover cinnamon-sugar on top.
Bake for 30-40 minutes, or until a wooden toothpick comes out clean.
Recipe by Faithful Provisions at https://faithfulprovisions.com/cinnamon-sugar-banana-bread/