Preheat oven to 350°F (175°C). Grease or line an 8×8-inch baking pan.

 In a large bowl, whisk together cocoa powder, flour, baking powder, and salt.

 Add shredded zucchini, sugar, oil, eggs, and vanilla extract to the dry ingredients. Stir until well combined.

 Fold in chocolate chips, if using.

 Pour the batter into the prepared pan and spread evenly.

 Bake for 25–30 minutes, or until a toothpick inserted comes out clean.

 Let cool completely before slicing into squares and serving!

Prep time: 10 mins
Yield: 16 brownies
Calories: ~150 per brownie