Preheat oven to 350°F (175°C). Grease a 9x5-inch loaf pan or line it with parchment paper.
Mash bananas in a large bowl until smooth.
Mix wet ingredients – stir in melted butter, sugar, eggs, and vanilla.
Whisk dry ingredients in another bowl – flour, baking soda, salt, and cinnamon.
Combine wet and dry mixtures gently (do not overmix).
Fold in walnuts or chocolate chips if using.
Pour batter into the prepared loaf pan.
Bake for 50–60 minutes, or until a toothpick comes out clean.
Let the super moist banana bread cool in the pan for 10 minutes before transferring to a wire rack.