Prepare the Cookie Dough:

1. Preheat the Oven: Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper or a silicone baking mat.
2. Mix Dry Ingredients: In a medium bowl, whisk together the flour, baking soda, and salt. Set aside.
3. Cream Butter and Sugars: In a large bowl, cream together the softened butter, brown sugar, and granulated sugar until light and fluffy. This usually takes about 2-3 minutes with an electric mixer.
4. Add Wet Ingredients: Beat in the egg and vanilla extract until well combined. Then, add the mashed bananas and mix until smooth and incorporated.
5. Combine Wet and Dry Ingredients: Gradually add the dry ingredients to the wet mixture, stirring until just combined. Be careful not to overmix.
6. Fold in the Chocolate Chips: Gently fold the chocolate chips (and nuts, if using) into the dough.

Shape and Bake the Cookies:

7. Scoop the Dough: Use a cookie scoop or tablespoon to drop rounded balls of dough onto the prepared baking sheet, spacing them about 2 inches apart.
8. Bake: Bake in the preheated oven for 15-18 minutes, or until the cookies are golden around the edges and a toothpick inserted into the center comes out clean.
9. Cool: Let the cookies cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.