Preheat your oven to 350°F (175°C).
Grate the medium zucchini using a box grater.
In a large mixing bowl, combine the shredded zucchini, unsweetened applesauce, brown sugar, egg, Greek yogurt, and vanilla extract. Mix until well blended.
Add the whole wheat flour, baking powder, baking soda, salt, and cinnamon. Stir until just combined.
Gently fold in the semi-sweet chocolate chips.
Line your muffin tin with parchment paper or muffin liners. Spoon the batter into each muffin cup, filling them about 2/3 full.
Bake for 18-22 minutes, or until a toothpick inserted into the center comes out clean.
Let the muffins cool in the tin for about 5 minutes, then transfer them to a wire rack to cool completely.
