Preheat oven to 350°F (175°C). Grease and flour a 9x5-inch loaf pan or line with parchment paper.
Prepare zucchini: Grate the zucchini using a box grater. Pat lightly with a paper towel to remove excess moisture, but don’t dry it completely.
Mix dry ingredients: In a medium bowl, whisk together flour, baking powder, baking soda, salt, cinnamon, and nutmeg.
Mix wet ingredients: In a large bowl, whisk eggs, oil, granulated sugar, brown sugar, and vanilla until well combined.
Combine: Add the dry ingredients to the wet mixture and stir until just combined—do not overmix.
Fold in zucchini and any optional add-ins like nuts or chocolate chips.