Preheat oven to 350 degrees F
Spray 13x9 baking dish with non-stick cooking spray and lightly dust with flour
Grate zucchini, set aside
In a large bowl, stir together sugar, vanilla extract, oil and eggs
In a medium bowl, whisk together flour, baking soda, salt, cinnamon, nutmeg and cloves
Add dry ingredients to wet ingredients and mix until smooth
Stir in zucchini and nuts if using
Pour mixture into prepared baking dish
Bake for 35-40 minutes or until toothpick inserted comes out clean
Remove from oven to cooling rack
Cool completely