Preheat the Oven: Preheat your oven to 350°F (175°C). Grease a loaf pan with butter or line it with parchment paper for easy removal.
Prepare Wet Ingredients: In a large bowl, combine mashed bananas, melted butter, granulated sugar, brown sugar, egg, and vanilla extract. Mix until smooth.
Combine Dry Ingredients: In a separate bowl, whisk together the flour, baking soda, and salt.
Mix Together: Add the dry ingredients to the banana mixture, stirring until just combined. Avoid overmixing.
Add Mix-ins: Gently fold in chocolate chips and walnuts.
Pour into Pan: Pour the batter into the prepared loaf pan, spreading it evenly.
Bake: Bake for 50-60 minutes, or until a toothpick inserted in the center comes out clean or with a few crumbs attached.
Cool and Serve: Allow the bread to cool in the pan for 10 minutes, then transfer it to a wire rack to cool completely before slicing.