Preheat the oven to 350°F. Grease a 9 x 5 inch loaf pan and line it with parchment paper.

In a medium bowl, whisk together the flour, baking soda, and salt.

In a large mixing bowl, beat the softened butter and brown sugar until smooth and creamy. Add the eggs and mix until fully combined.

Stir in the sourdough discard, mashed bananas, and vanilla. Add the dry ingredients and mix gently just until no large streaks of flour remain. Fold in the chocolate chips and walnuts, if using.

Pour the batter into the prepared loaf pan and smooth the top. Sprinkle with additional chocolate chips if desired.

Bake for 55 to 65 minutes, until the top is golden brown and a toothpick inserted near the center comes out with a few moist crumbs but no wet batter.

Let the bread cool in the pan for 10 to 15 minutes. Transfer it to a wire rack and allow it to cool before slicing.