Preheat your oven to 350°F and grease a 9x5 inch loaf pan.
In a bowl, whisk together the flour, baking soda, baking powder, cinnamon, and salt.
In another bowl, beat the eggs with the sugar until smooth. Add the oil and vanilla and mix again.
Stir the grated zucchini into the wet mixture.
Add the dry ingredients to the wet ingredients and stir just until combined.
Fold in the nuts if using.
Pour the batter into the prepared loaf pan and bake for 50–60 minutes, until a toothpick comes out clean.
Let the bread cool in the pan for 10 minutes before transferring to a wire rack.