Prep oven: Preheat oven to 175°C (350°F). Grease and line a 22x12 cm loaf pan.
Mash bananas: In a mixing bowl, mash bananas until smooth.
Mix wet ingredients: Stir in melted butter, sugar, eggs, and vanilla until well combined.
Add dry ingredients: Fold in flour, baking soda, and salt. Mix gently until just combined.
Optional mix-ins: Fold in walnuts or chocolate chips if desired.
Bake: Pour batter into loaf pan. Bake 50–55 minutes, until a toothpick inserted in the center comes out clean.
Cool & serve: Allow to cool in pan 10 minutes, then transfer to a wire rack. Slice and serve.