Preheat the oven to 350°F (175°C) and line a baking sheet with parchment paper.

In a mixing bowl, combine the dry ingredients: flour, baking soda, baking powder, salt, and cinnamon.

In another bowl, mix the wet ingredients: grated zucchini, brown sugar, granulated sugar, vegetable oil, egg, and vanilla extract until well combined.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Fold in chocolate chips and walnuts if using.

Drop spoonfuls of the cookie dough onto the prepared baking sheet, spacing them about 2 inches apart.

Bake in the preheated oven for 15-20 minutes, or until the edges are lightly golden.

Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.