Prep: Preheat oven to 350°F (175°C). Grease a 9x5-inch loaf pan or line with parchment paper.
Dry Ingredients: In a medium bowl, whisk flour, baking powder, baking soda, salt, cinnamon, and nutmeg.
Wet Ingredients: In a large bowl, beat eggs, granulated sugar, brown sugar, oil, and vanilla until smooth.
Combine: Fold grated zucchini into wet ingredients. Gradually add dry ingredients, mixing just until combined. Stir in nuts (if using).
Bake: Pour batter into the prepared pan. Bake 50–60 minutes, or until a toothpick inserted comes out clean.
Cool: Let cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.