Preheat oven to 325 degrees F and grease a 9x5 nonstick loaf pan with cooking spray. Line the pan with parchment paper with enough paper to let it hang off the sides of the pan.
Using a sifter, sift together dry ingredients into a large bowl. Set aside.
Grate the zucchini, using a box grater and set aside.
Whisk together the sugars and the remaining wet ingredients until everything has fully combined.
Pour the wet ingredients into the dry mixture and, using a spatula, stir until the mixture starts to combine.
Gently fold in zucchini and stir until everything has been fully incorporated. Be sure to not over mix!
Pour the mixture into the prepared pan, only filling it up about 3/4 of the way full. You will have leftover batter for about 4 muffins.
Bake the loaf for about 45-60 minutes, or until a toothpick comes out clean.*
Remove from the oven and let cool in the pan on a wire rack until cool enough to remove from the pan.
*If the top of the bread starts getting too brown, cover with foil and continue baking!** If making leftover batter into muffins/mini loaves, line with muffin liners and bake about 20-30 minutes. Before baking, fill empty muffin slots with water.