Preheat oven to 350°F (175°C). Grease and flour two 8×4-inch loaf pans.

In a large bowl, whisk together flour, cinnamon, salt, baking powder, baking soda, and nutmeg.

In another bowl, beat eggs, oil, sugar, and vanilla until well combined.

Stir the dry ingredients into the wet mixture until just combined.

Fold in the grated zucchini and walnuts (if using) until evenly mixed.

Pour the batter into the prepared loaf pans.

Bake for 40 to 60 minutes or until a toothpick inserted in the center comes out clean.

Let the bread cool in the pans for 20 minutes. Then remove and cool completely on a wire rack.