Preheat the oven to 350°F (175°C). Grease and line a 9×13-inch pan (or two 8-inch round pans) with parchment paper.
Grate the zucchini and lightly squeeze out excess moisture using a clean towel or paper towels. Do not over-squeeze.
In a large bowl, whisk together eggs, sugar, oil, and vanilla extract until smooth and well combined.
In a separate bowl, combine flour, baking powder, baking soda, cinnamon, nutmeg, and salt. Mix well.
Add dry ingredients to wet and mix gently until just combined.
Fold in zucchini and any optional mix-ins like nuts or chocolate chips. The batter will be thick.
Spread batter evenly into the prepared pan.
Bake for 35–40 minutes, or until a toothpick inserted into the center comes out clean.
Cool in the pan for 10 minutes, then transfer to a wire rack to cool completely before frosting or serving.