Preheat your oven to 350°F and spray a 9x5 inch loaf pan with cooking spray.
In a large bowl, combine the grated zucchini, granulated sugar, brown sugar, applesauce, oil, eggs, and vanilla. Whisk until smooth.
Add the flour, baking powder, baking soda, salt, and cinnamon to the bowl. Stir gently until no dry flour is visible, being careful not to overmix.
Pour the batter into the prepared loaf pan, smoothing the top with a spatula.
Bake for 50 to 54 minutes, or until a toothpick inserted into the center comes out with moist crumbs. Cool in the pan for 10 minutes, then transfer to a wire rack.
Refrigerate the bread for at least 12 hours before serving for optimal flavor and texture.
Notes
For best results, grate the zucchini finely.
Store the bread covered in the refrigerator to keep it moist, and feel free to add nuts or chocolate chips for extra texture.