Preheat your oven to 350°F (175°C). Grease a 9x5-inch loaf pan with butter or cooking spray, then dust lightly with flour.

In a large bowl, whisk together flour, salt, baking soda, cinnamon, and nutmeg until well combined.

In a separate bowl, beat together eggs, vegetable oil, granulated sugar, brown sugar, and vanilla extract until smooth and well combined.

Add the grated zucchini to the wet ingredients and stir to combine.

Pour the wet ingredients into the dry ingredients and gently fold together with a wooden spoon or spatula until just combined. Don't overmix—a few lumps are fine.

If using walnuts, fold them in gently.

Pour the batter into the prepared loaf pan and spread evenly. Bake for 55-65 minutes, or until a toothpick inserted in the center comes out with just a few moist crumbs.

Cool in the pan for 10 minutes, then turn out onto a wire rack to cool completely before slicing. Store covered at room temperature for up to 3 days.