Heat your oven to 350 degrees F. Line two baking sheets with parchment paper and set aside.

Grate the zucchini on the large holes of a box grater. Wrap it tightly in a clean kitchen towel and squeeze firmly over the sink until most of the liquid is out. Measure 3/4 cup of the squeezed zucchini and set it aside. The drier it is, the better your cookies will hold their shape.

In a large bowl, mash the bananas with a fork until as smooth as you can get them. A few small lumps are fine. Add the brown sugar, melted butter, egg, and vanilla and stir everything together until combined.

Add the flour, baking soda, baking powder, salt, and cinnamon directly to the bowl. Stir until just combined and no dry streaks remain. Do not overmix.

Fold in the squeezed zucchini and your chocolate chips, pecans, or a mix of both. The dough will be soft and a little looser than a standard drop cookie dough because of the banana moisture.

Scoop the dough by rounded 2-tablespoon portions onto the prepared baking sheets, spacing them about 2 inches apart. These cookies spread only a little, so you can fit about 10 per sheet. Gently flatten the tops just slightly with your fingers if you like a more uniform cookie.

Bake one sheet at a time on the center rack for 10 to 12 minutes, until the bottoms are golden and the edges look set. The tops will look soft and slightly matte when done. Pull them at the low end of the time range for a softer center.

Let the cookies sit on the baking sheet for 5 minutes before moving them to a wire rack. They firm up as they cool. Cool completely before storing, since the banana makes them a little more delicate when warm.