In a large bowl, whisk together flour, baking powder, baking soda, salt, cinnamon, nutmeg, and sugars.
In a separate bowl, whisk together buttermilk, melted butter, eggs, and vanilla extract. Pour liquid ingredients over dry ingredients, stirring until just combined. Fold in the zucchini.
Heat a griddle or pan to medium heat. Spray with cooking spray. Pour about a 1/3 cup of batter onto heated skillet. Cook until surface of pancakes have some bubbles and a few have burst, about 3 minutes. Flip carefully with a spatula, and cook until browned on the underside.
Continue making pancakes until the batter is gone. Serve pancakes with butter and maple syrup, if desired.
We use white whole wheat flour, but you can use all-purpose flour, whole wheat flour, or gluten-free flour. The pancakes can be frozen for up to 2 months.