Preheat your oven to 350°F (175°C). Grease a 9×5-inch loaf pan or line it with parchment paper for easy removal.
Prepare the zucchini. Grate the zucchini using the large holes of a box grater. Lightly squeeze out excess moisture using a clean kitchen towel, but don’t overdo it, some moisture keeps the bread tender.
Mix the dry ingredients. In a medium bowl, whisk together flour, baking powder, baking soda, salt, cinnamon, and nutmeg.
Combine the wet ingredients. In a large bowl, whisk together oil, granulated sugar, brown sugar, eggs, and vanilla until smooth and slightly frothy.
Combine everything. Add the dry ingredients to the wet mixture and stir gently until just combined. The batter should be thick but pourable. Do not overmix — this keeps the loaf tender.
Fold in zucchini and any optional mix-ins like nuts or chocolate chips.
Pour into the prepared pan and smooth the top with a spatula.
Bake for 50–60 minutes, or until a toothpick inserted in the center comes out clean.
Cool completely on a wire rack before slicing. The flavor actually deepens after a few hours, so it’s even better the next day.