Preheat oven to 350F. Prepare a 12 cup muffin tin by spraying with baking spray or lining with cupcake liners.
In a large bowl combine flour, sugar, baking soda, baking powder, cinnamon, salt, and cocoa powder, and stir to combine.
Add milk, egg, vanilla extract, and olive oil, and stir to combine.
Add shredded zucchini and stir until well incorporated. Add chocolate chips and fold in. Batter should be fairly thick.
Fill cupcake tins about 2/3 of the way full with batter. The batter should be evenly distributed among the 12 cupcake cups.
Bake for 20-25 minutes, or until muffins are risen and baked in the middle.
Allow muffins to cool in the tins for 5 minutes, and then remove and let finish cooling on a cooling rack.