Preheat the oven to 350°F. Grease a 4x8-inch loaf pan with cooking spray or butter.
Mix all the dry ingredients - flour, sugar, walnuts, baking soda, and salt till they are combined.
In a mixing bowl, mash the ripe bananas until smooth. Add the melted butter, vanilla extract, and egg and mix them well. Add the flour mixture and mix them in till they are combined.
Pour the batter into the greased pan and bake for 50 - 60 minutes until a toothpick inserted in the center comes out clean. (I checked at the 50-minute mark and the banana bread was done)
Remove from the oven and let the bread cool in the pan for a few minutes before transferring it on a wire rack to cool completely.
Use a serrated knife to cut the bread into slices.