Instructions:

1. Preheat the oven to 350°F (175°C) and grease a 9x5-inch loaf pan.
2. In a large bowl, mash the bananas with a fork until smooth.
3. Add the melted butter, sugar, egg, and vanilla extract to the mashed bananas and mix well.
4. In a separate bowl, whisk together the flour, baking soda, and salt.
5. Add the dry ingredients to the wet ingredients and mix until just combined.
6. Pour the batter into the prepared loaf pan and smooth the top with a spatula.
7. Bake for 50-60 minutes, or until a toothpick inserted into the center comes out clean.
8. Let the bread cool in the pan for 10 minutes, then remove it from the pan and cool completely on a wire rack.