Preheat oven to 350° F. Spray an 8½ by 4½-inch or 12 by 4½-inch loaf pan with nonstick spray and set aside.
In a large bowl, whisk together the flour, baking soda, salt, nutmeg, and cinnamon. Make a well in the center and add the zucchini, oil, eggs, water, vanilla, and nuts (if using). Whisk to combine and then switch to a spoon or spatula to finish mixing completely.
Pour into prepared pan. Bake for 50-60 minutes, or until a toothpick inserted into center comes out clean.
For muffins, line muffin pan with paper liners and fill all the way to the top with batter. Bake for 20-25 minutes, or until springs back when lightly touched (or a toothpick inserted into center comes out clean).
Remove from the oven and place on a wire rack to cool for 10 minutes in the pan. Remove bread from the pan and allow to cool completely before cutting and serving.
Leftovers can be tightly wrapped and stored at room temperature for 3 days or frozen for up to 3 months.