Preheat the oven to 350°F. Line an 8-inch square baking pan with parchment paper.

Finely grate the zucchini and gently pat it with paper towels so it is not dripping wet.

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

In a large bowl, whisk the melted butter, brown sugar, and granulated sugar until smooth. Add the eggs and vanilla and whisk until thick and glossy.

Fold the dry ingredients into the wet ingredients just until no dry streaks remain.

Fold in the shredded zucchini until the batter becomes glossy and spreadable. Stir in the chocolate chips if using.

Spread the batter evenly in the prepared pan and smooth the top.

Bake for 28 to 32 minutes, until the top is set and slightly crinkly and a toothpick inserted near the center comes out with moist crumbs.

Cool completely in the pan before lifting out and slicing into 12 brownies.