Preheat oven to 375 degrees F.

Grease 2 standard muffin pans

In a medium bowl, combine flour, baking powder, baking soda, salt and cinnamon. Set aside.

In a large bowl, whisk together melted butter, milk, sour cream, eggs, and vanilla until combined.

Add white and brown sugars and whisk until the mixture is smooth.

Add dry ingredients and stir until combined and there are no lumps or pockets of flour.

Gently fold in the grated zucchini and chocolate chips.

Use a ¼ cup measuring cup to fill the wells of the prepared muffin tins ¾ the way full.

Bake the muffins in the preheated oven for 15-18 minutes, or until a toothpick inserted in the center comes out clean or with a few moist crumbs and the tops spring back when lightly pressed.

Let the muffins cool slightly in the muffin pans for 5 minutes.

Then, release the sides of the muffins. Remove each muffin and transfer it to a wire rack to cool.