01 - Preheat oven to 350°F. Line a 12-cup muffin tin with paper liners or apply nonstick spray to each cup.
02 - In a large mixing bowl, whisk together flour, baking powder, baking soda, salt, cinnamon, and nutmeg until evenly distributed.
03 - In a separate medium bowl, beat eggs. Add vegetable oil, granulated sugar, brown sugar, and vanilla extract; whisk until smooth and fully combined.
04 - Fold the wet mixture into the dry ingredients using a spatula until just combined. Do not overmix, as this can result in dense muffins.
05 - Gently fold grated zucchini and any optional add-ins into the batter until evenly distributed.
06 - Divide batter evenly among prepared muffin cups, filling each approximately 3/4 full.
07 - Bake for 22 to 25 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
08 - Allow muffins to cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.