Preheat oven to 350 degrees. Spray a loaf pan with non-stick cooking spray.
Add the stick of butter to a bowl, microwave for 45 seconds, or until melted.
Add bananas to bowl and mash with a fork.
Add the vanilla extract and eggs to the bowl. Use fork to stir thoroughly.
In another bowl, whisk together flour, sugar, baking soda, salt, and cinnamon.
Add the dry ingredients and wet ingredients together and mix/combine with spatula.
Pour the batter into loaf pan and bake for 45-50 minutes. Insert toothpick to check for dryness.
