Preheat oven to 350°F (175°C). Grease a 9x5-inch loaf pan or line with parchment paper.
Wash and trim zucchini; grate using the large holes of a box grater until you have 2 cups. Lightly squeeze to remove excess liquid.
In a large bowl, whisk eggs, oil, sugar, and vanilla until smooth.
In a separate bowl, combine flour, salt, baking soda, baking powder, and cinnamon.
Fold dry ingredients into wet mixture until just combined.
Stir in grated zucchini and optional nuts or chocolate chips.
Pour batter into prepared loaf pan and bake for 50–60 minutes, or until a toothpick inserted in the center comes out clean.
Let cool in pan for 10 minutes, then transfer to a cooling rack. Slice when fully cooled.