Preheat your oven to 350°F (175°C). Grease a 9x5-inch loaf pan or line it with parchment paper.
In a medium bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, and nutmeg. Set aside.
In a large bowl, combine the granulated sugar, brown sugar, and vegetable oil. Mix until well combined.
Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract, grated zucchini, lemon zest, and lemon juice until fully incorporated.
Gradually add the dry ingredients to the wet ingredients, stirring until just combined. Be careful not to overmix. If using, fold in the chopped nuts.
Pour the batter into the prepared loaf pan and smooth the top.
Bake for 50-60 minutes, or until a toothpick inserted into the center comes out clean.
Allow the bread to cool in the pan for about 10 minutes before transferring it to a wire rack to cool completely.