Heat griddle to low and allow to get nice and hot for several minutes. Grease with butter.
Combine eggs, eggnog, vanilla, cinnamon, and nutmeg in a shallow dish. Soak slices of bread for several minutes on both sides. Place on greased griddle and allow to cook until golden brown on both sides, about 10-15 minutes total.
Serve with a dusting of powdered sugar and/or real maple syrup.