Preheat the oven to 350℉, and butter a 4x8-inch metal loaf pan.
In a mixing bowl, mash 3 overripe bananas with a fork. Stir ⅓ cup of melted butter into the mashed bananas and continue to stir until completely smooth.
In the same mixing bowl, stir in 1 beaten egg, and 1 teaspoon of vanilla extract
In a separate mixing bowl, mix 1 teaspoon of baking soda, ½ teaspoon of salt, ¾ cup of sugar, and 1½ cups of all-purpose flour.
Pour the dry ingredient mixture into the wet ingredients. Mix well.
Pour the batter in the buttered loaf pan. Bake for 55 minutes at 350℉. Insert a toothpick in the center. If it comes out clean, it is done.
Remove from oven and let cool in the pan for 5-10 minutes. Gently remove the banana bread from the pan and let the bread cool for an additional 2 minutes.