Preheat the oven to 350°F (175°C).

Grease a loaf pan with butter or cooking spray.

In a mixing bowl, mash the ripe bananas with a fork until smooth.

Stir the melted butter into the mashed bananas until combined.

In a separate bowl, whisk together the baking soda, salt, and flour.

Add sugar, beaten egg, and vanilla extract to the banana mixture and stir until blended.

Gradually fold the flour mixture into the banana mixture until just combined, being careful not to overmix.

Pour the batter into the prepared loaf pan and smooth the top.

Bake for 60 minutes, or until a toothpick inserted into the center comes out clean.

Let the bread cool in the pan for 10 minutes, then transfer to a wire rack to cool completely before slicing.