Preheat the oven to 425℉. Line the muffin tin with 12 liners and set aside. Shred the zucchini on the thick side of the grater and set aside.
1 1/2 cups zucchini
In a large bowl, add in the dry ingredients. Mix together and set aside.
2 cups all-purpose flour, 1 1/4 cups white sugar, 1/2 cup unsweetened cocoa powder, 1 tsp baking soda, 2 tsp baking powder, 1/2 tsp salt
Into the medium bowl add in the wet ingredients. Whisk together until well combined.
2/3 cups oil, 2 eggs, 1 egg yolk, 1 tbsp vanilla, 1 cup sour cream
Add the wet ingredients into the dry. With a spatula, mix until a chocolate muffin batter forms. Don't over-mix.
Add the shredded zucchini and chocolate chips and mix in a few times. Continue mixing until no flour streaks are left. Do not over-mix!!
1/2 cup mini chocolate chips, 1 1/2 cups zucchini
Evenly divide the batter between 12 liners, they should be almost or all the way full. Using a cookie scooper helps big time to minimize the mess.
Bake the muffins at 425°F for 6 minutes. Then turn the oven down to 350°F and continue baking for 12-16 minutes. Mine took 15 minutes exactly. The muffins are ready when a toothpick inserted comes out clean.
Enjoy!