Preheat the oven to 350°F (175°C). Grease a 9×5 inch loaf pan with butter or non-stick spray.
In a large mixing bowl, mash the ripe bananas with a fork until smooth.
Add the melted butter to the mashed bananas and mix well.
Stir in the granulated sugar, beaten egg, and vanilla extract until combined.
Sprinkle the baking soda and salt over the mixture and stir to combine.
Add the all-purpose flour last and mix until just incorporated. Do not overmix.
Pour the batter into the prepared loaf pan and spread it evenly.
Bake in the preheated oven for 60 minutes, or until a toothpick inserted into the center comes out clean.
Remove the banana bread from the oven and let it cool in the pan for 10 minutes.
Transfer the bread to a wire rack to cool completely before slicing and serving.