Preheat oven to 350ºC (177ºC) and line a 12-cup muffin pan with muffin liners or spray with non-stick cooking spray.
In a large bowl, whisk together flour, baking powder, baking soda, salt, cinnamon and nutmeg.
In a medium-sized bowl, whisk together eggs, oil, granulated sugar, dark brown sugar, vanilla and milk. Add grated zucchini and mix until just combined. If using any add-ins, fold them in now.
Scoop batter evenly among the 12 cups and bake for 22-24 minutes until golden and a tester comes out clean. Let cool in pan for 10 minutes so the muffins are easy to remove then transfer to a wire cooling rack.