Preheat oven to 350°F (175°C). Grease a 9x5-inch loaf pan or line it with parchment paper.
In a bowl, whisk flour, baking soda, and salt. Set aside.
In another bowl, mix melted butter and sugar. Add the egg, vanilla, and mashed bananas, stirring until smooth.
Gradually add dry ingredients to the wet mixture, mixing until just combined. Avoid overmixing.
Gently fold in chocolate chips (and walnuts if using).
Pour batter into the loaf pan. Optional: Sprinkle extra chocolate chips on top.
Bake for 55–60 minutes or until a toothpick inserted comes out clean (a few crumbs are okay).
Let cool in the pan for 10 minutes, then transfer to a wire rack. Slice once fully cooled.
