Preheat your oven to 350℉ (177℃). Lightly grease and flour an 8.5x4.5-inch loaf pan or spray it with baking spray.
In a large bowl, mash the ripe bananas until smooth, then add the melted butter. Mix in the granulated sugar, beaten egg, and pure vanilla extract, stirring well until fully combined.
Sprinkle the baking soda, baking powder, ground cinnamon, and salt over the banana mixture. Stir gently to incorporate these dry ingredients without overmixing.
Gradually add the all-purpose flour to the batter along with the chopped walnuts or chocolate chips if desired. Stir until just combined; be careful not to overmix.
Pour the batter into your prepared loaf pan and smooth out the top with a spatula if needed. Bake for about 50-60 minutes, or until a knife inserted in the center comes out clean.
Once baked, allow the banana bread to cool in the pan for about 10 minutes before turning it out onto a wire rack to cool completely. Slice into thick pieces and enjoy.