Preheat your oven to 350°F (175°C).
In a mixing bowl, mash the ripe bananas with a fork until smooth.
Add melted butter to the mashed bananas and mix well.
Stir in baking soda and salt.
Add sugar, beaten egg, and vanilla extract; mix until combined.
Gradually add flour, stirring until just incorporated.
If desired, fold in chopped walnuts.
Pour the batter into a greased loaf pan.
Bake for about 60 minutes or until a toothpick comes out clean.
Allow the bread to cool before slicing and serving.