Preheat your oven to 350°F (175°C).
Grease a 9x5-inch loaf pan or line it with parchment paper.
In a large bowl, mash the ripe bananas with a fork until they reach a smooth consistency.
Stir in the melted butter until well combined, then add sugar, beaten egg, and vanilla extract. Mix everything together until you achieve an even blend of wet ingredients.
Sprinkle baking soda and salt over the mixture, stirring gently to combine them without overmixing. Gradually fold in flour just until it disappears.
Pour the batter into the prepared loaf pan and spread it evenly. Bake for 50 to 60 minutes or until a toothpick inserted in the center comes out clean; then let it cool before slicing.