Preheat your oven to 350°F (175°C). Grease a 9x5-inch loaf pan with butter or non-stick spray, then lightly dust with flour or line with a parchment paper sling for easy removal.

Grate the zucchini using the large holes of a box grater. Spread it on a clean paper towel and press gently to absorb excess surface moisture. Set aside. Do not wring it out completely — you need some of that moisture in the batter.

In a large bowl, whisk together the all-purpose flour, cinnamon, nutmeg, baking soda, baking powder, and salt until evenly combined. Set aside.

In a separate medium bowl, whisk together the eggs, granulated sugar, and brown sugar until smooth and slightly thickened, about 1 minute. Whisk in the vegetable oil and vanilla extract until fully incorporated.

Fold the grated zucchini into the wet ingredient mixture until evenly distributed.

Pour the wet ingredients into the dry ingredients and fold together with a rubber spatula until just combined — do not overmix. A few small lumps are completely fine and desirable. If using chocolate chips or walnuts, fold them in now.

Pour the batter into the prepared loaf pan and spread into an even layer. Optionally, sprinkle a light layer of granulated sugar or cinnamon sugar over the top for a sparkling, slightly crunchy crust.

Bake on the center rack for 55–65 minutes, until a toothpick inserted into the very center of the loaf comes out clean or with just a few moist crumbs (not wet batter). If the top is browning too quickly around the 40-minute mark, tent loosely with aluminum foil and continue baking.

Remove from the oven and let the loaf cool in the pan on a wire rack for 10–15 minutes before turning it out. Allow to cool for at least 20 more minutes before slicing for the cleanest cuts and best texture.