Preheat your oven to 350°F (175°C) and line a muffin tin with paper liners or grease it lightly.
In a large bowl, whisk together the flour, cocoa powder, baking soda, baking powder, salt, and cinnamon.
In another bowl, mix the granulated sugar, brown sugar, eggs, vegetable oil, and vanilla extract until well combined.
Add the grated zucchini to the wet ingredients and stir until evenly mixed.
Gradually add the dry ingredients to the wet mixture, stirring gently until just combined. Be careful not to overmix.
Fold in the chocolate chips.
Spoon the batter into the prepared muffin tin, filling each cup about ¾ full.
Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean.
Allow the muffins to cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.