Preheat your oven to 350 F. Generously spray a standard muffin tin and set aside
With a handheld grater or in your food processor with the shredder attachment, shred your zucchini. Using a cheesecloth or a fine-mesh strainer, squeeze any excess liquid out of the zucchini.
In a medium bowl combine flour, cocoa powder, baking powder, baking soda, salt, and cinnamon.
In a separate bowl, whisk together oil and both sugars. Add apple sauce, milk, and vanilla extract. Stir to combine. Fold in shredded zucchini.
Add the wet ingredients to dry and mix until the dry ingredients are fully incorporated and a uniform batter has formed. Fold in chocolate chips.
Evenly scoop batter into the prepared muffin tin. The batter should be nearly to the top. Bake for 20-25 minutes until a knife inserted in the middle come out clean.
Remove from oven and let the cake cool for 10 minutes before flipping it out onto a wire cooling rack to let cool all the way.
Serving and Storing - Store leftover muffins in an airtight container at room temperature for up to 5 days. You can also freeze these muffins for up to 2 months. To thaw, pull the muffins from the freezer and let them thaw at room temperature for several hours.
Variations - Swap out chocolate chips for walnuts for a walnut chocolate zucchini muffin.