Preheat the oven to 350 degrees.
In a large bowl, whisk the dry ingredients together (flour, cocoa, baking powder, baking soda, salt, and cinnamon).
In a separate bowl, mix the wet ingredients (applesauce, egg, oil, sweetener, milk, vanilla, vinegar, stevia, and zucchini).
Make a well in the center of the dry mix, and pour in the wet ingredients.
Gently mix together the batter, trying not to mix it more than 15 times.
Using an ice cream scoop or small measuring cup, dollop the batter equally among 12 paper muffin cups.
Top each with a few chocolate chips, if desired.
Bake the muffins for 14-15 minutes (tops should be springy to the touch).
Cool 5-10 minutes and enjoy!