Preheat oven to 350°F (175°C). Grease a 9×5‑inch loaf pan or line with parchment.
5 min
In a bowl, whisk mashed bananas with melted butter and sugar until combined
1-2 min
Whisk in egg and vanilla. Sprinkle baking soda and salt over the top; whisk to combine
1 min
Add flour and gently fold just until no dry streaks remain. Fold in walnuts or chips if using. Don’t overmix
1-2 min
Pour into pan, smooth the top, and bake until a tester comes out clean
50-60 min
Cool in pan 10 minutes, then lift out and cool fully before slicing.