Heat oven to 350° F (177° C). Lightly grease a 5-inch baking dish (or use a dish of similar size) with cooking spray or butter.
In a medium-sized bowl, add the grated zucchini, sugar, brown sugar, applesauce, oil, egg, and vanilla. Stir until well combined.
Add the flour, baking powder, baking soda, cinnamon, and salt. Stir until no flour remains, being careful not to overmix.
Pour the batter into the baking dish and bake for 30 minutes. A toothpick inserted in the center should come out clean.
Cool in the pan for 10 minutes. Remove from the pan and transfer to a wire cooling rack to cool completely.
Slice and enjoy or store wrapped at room temperature.
Notes
To measure flour correctly, use a spoon to stir the flour inside the container. You want to loosen it up in case it's packed tightly inside. Use a spoon to scoop flour into a dry measuring cup and slightly overfill. Then, use the flat end of a knife or other straight edged utensil to level the flour across the cup. Do not scoop the flour. When you scoop, the flour gets packed too tightly and you will end up with more flour than the recipe calls for.Expert Tips
Grating Zucchini: No need to peel the zucchini before grating. The skin adds extra nutrients.
Do Not Squeeze The Zucchini: The moisture is required to keep the loaf moist.
Checking Doneness: A toothpick inserted in the center should come out clean when the bread is done.
Storing: Keep the bread in an airtight container at room temperature for up to 2 days, or refrigerate to extend its freshness.