Preheat your oven to 350°F. For easier cleanup, line a 9x13-inch pan with foil and spray it generously with cooking spray. Set aside.

In a large mixing bowl, whisk together the sugar, cocoa powder, oil, and vanilla until well combined.

Add the flour, salt, and baking soda to the mixture. Using a rubber spatula, fold and mix until combined. The batter will be dry and crumbly at this point, which is normal.

Grate the zucchini using the coarsest blade of a large box grater. Add 3 cups of loosely packed zucchini to the batter. Do not wring out the zucchini.

Fold the zucchini into the batter with a rubber spatula. Let the mixture sit for about 20 minutes, stirring every 5 minutes. This allows the zucchini to release its moisture, making the batter more fudge-like.

After 20 minutes, stir in 1 cup of mini chocolate chips. Pour the batter into the prepared pan and spread it evenly.

Sprinkle the remaining mini chocolate chips (about 2/3 to 3/4 cup) over the top of the batter.

Bake for approximately 30 minutes, or until a toothpick inserted in the center comes out clean or with a few moist crumbs. Start checking at 25 minutes and rotate the pan midway through baking for even cooking.

Allow the brownies to cool in the pan for 30 to 60 minutes before slicing and serving. Extra brownies can be stored in an airtight container at room temperature for up to 5 days or frozen for up to 4 months.