Preheat oven to 350 °F (175 °C). Line a 12-cup muffin tin with paper liners or grease well.
In a medium bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, and nutmeg.
In a large bowl, whisk the eggs until just blended. Add granulated sugar, brown sugar, oil, and vanilla; whisk until smooth.
Stir the grated zucchini into the wet ingredients.
Pour the dry ingredients into the wet mixture and gently fold until just combined. Do not overmix—you want a few streaks of flour remaining.
Fold in nuts or chocolate chips, if using.
Divide the batter evenly among the 12 muffin cups, filling each about ¾ full.
Bake for 18–22 minutes, or until a toothpick inserted into the center of a muffin comes out clean or with a few moist crumbs.
Let muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.
Notes & Tips
To remove excess zucchini moisture, grate onto paper towels and squeeze gently.
For a healthier twist, substitute half the all-purpose flour with whole wheat flour.
Store muffins in an airtight container at room temperature for up to 3 days or freeze for up to 1 month.
