Preheat your oven to 375°F. Line a 12-cup muffin tin with paper or silicone liners.
Prep the zucchini: Shred 1 ½ cups of zucchini using a box grater or food processor shredding disc. Transfer to a bowl, toss with a pinch of salt, and let it sit for 5 minutes. Then gently squeeze handfuls of the shreds over the sink to remove excess moisture—you want it damp, not dripping dry. Set aside.
Mix wet base: In a large mixing bowl, whisk together the oil, granulated sugar, brown sugar, eggs, and vanilla until smooth and slightly paler, about 30 seconds.
Fold the shredded zucchini into the wet mixture. It will look separate at this point—that's fine.
Add dry ingredients: In a small bowl (or on top of the wet mixture, lazy method), whisk together the flour, baking powder, baking soda, cinnamon, nutmeg, and salt. Then gently fold the dry ingredients into the wet with a spatula just until no streaks of flour remain. A few lumps are fine—do not overmix.
Divide the batter evenly among the 12 muffin cups, filling each almost to the top (about ¾ to ⅞ full). Use a cookie scoop for even portions. Sprinkle a pinch of raw sugar or flaky salt on each muffin if desired.
Bake at 375°F for 18–22 minutes, until a toothpick inserted into the center comes out clean or with just a few moist crumbs. Let the muffins cool in the tin for 5 minutes, then transfer to a wire rack to cool completely (at least 20 minutes) before storing.