Preheat the oven to 350°F (175°C). Grease a loaf pan well.
In a large bowl, mash the ripe bananas until smooth.
Stir in the melted butter until combined.
Mix in the sugar, beaten egg, and vanilla extract.
Sprinkle in the baking soda and salt; stir gently to combine.
Add the flour and stir until just combined — avoid overmixing.
Pour the batter into the greased loaf pan and smooth the top.
Bake for 50–60 minutes, or until a toothpick inserted into the center comes out clean.
Let the bread cool in the pan for about 10 minutes, then transfer it to a wire rack to cool completely (or slice while still slightly warm if preferred).