Prepare the Oven
Preheat oven to 350°F (175°C).
Grease or line a 9x5-inch loaf pan with parchment paper.
Prepare the Zucchini
Grate the zucchini using the large holes of a box grater.
Do not peel it. The peel is tender and adds color and nutrients.
Lightly pat the zucchini with a paper towel to remove excess moisture, but don't squeeze it completely dry.
Mix the Dry Ingredients
In a large bowl, whisk together:
Flour
Baking soda
Baking powder
Cinnamon
Nutmeg
Salt
Mix the Wet Ingredients
In another bowl, whisk together:
Eggs
Oil
Applesauce
Granulated sugar
Brown sugar
Vanilla
Combine
Add the wet ingredients to the dry ingredients and stir just until combined.
Fold in the grated zucchini and any optional mix-ins.
Do not overmix.
Bake
Pour the batter into the prepared loaf pan.
Bake for 50–60 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs.
Cool
Cool in the pan for 10 minutes before transferring to a wire rack to cool completely.