Preheat oven to 350°F. Spray 9 x 5-inch loaf pan with nonstick spray and line with parchment paper that hangs over the edge of pan. Spray parchment paper; set aside.
Whisk the flour, baking powder, baking soda, salt, cinnamon, and nutmeg together in a large bowl until thoroughly combined; set aside.
In medium bowl, whisk together oil, brown sugar, granulated sugar, eggs, applesauce, and vanilla together until combined; whisk in the zucchini.
Pour the wet ingredients into the dry ingredients. Gently stir or whisk until combined; do not overmix.
Fold in any optional add-ins like nuts, etc.
Spread the batter evenly into prepared loaf pan. Bake for 55-70 minutes.
During last 15 minutes of baking time, tent the bread loosely with aluminum foil to prevent over browning on top.
The bread is done when a toothpick inserted in the center comes out *mostly* clean with zero raw batter; a few crumbs are okay.
Remove the bread from the oven and set on a wire rack. Cool in pan for 10 minutes before lifting bread from pan using paper edges. Return to wire rack to cool completely. For neat slices, allow bread to cool completely.
Cover and store leftover bread at room temperature for up to 3-4 days or in the refrigerator for up to 1 week.
To freeze, cool completely and wrap in plastic wrap or aluminum foil and then place in freezer bag. Freeze up to 3 months for best flavor. Thaw overnight in the fridge