Preheat your oven to 350 degrees F and spray a muffin tin with baking spray.
Grate both zucchini with the skin on. Place the grated zucchini in a fine mesh sieve over a bowl and press down on the zucchini to extract as much liquid as possible. Discard the juice and place the dried zucchini in a large mixing bowl.
2 zucchini, grated and strained
Add the eggs, sugar, and vanilla to the mixing bowl with the zucchini and stir, breaking up the eggs well.
2 eggs, 1 ⅓ cup light brown sugar, 1 Tablespooon vanilla extract
Stir in the melted butter.
¾ cup melted butter
Add the flour, baking soda, baking powder, cinnamon, nutmeg, and salt to the bowl and stir into a thick batter.
2 ¾ cup flour, 1 teaspoon baking soda, 1 teaspoon baking powder, 1 Tablespoon cinnamon, ½ teaspoon ground nutmeg, ½ teaspoon salt
Stir in the chocolate chips, if using.
1 cup chocolate chips (optional)
Scoop the batter into the prepared muffin tin, filling each muffin cup to the top.
Bake for about 25 minutes. The tops of the muffins will be golden brown and a toothpick inserted into the center of the muffin will come out cleanly.
Let the muffins cool for about 10 minutes in the pan and then flip them out onto a metal cooling rack. Cool for another 10 minutes then enjoy!