Add the eggs, milk, vanilla, cinnamon, nutmeg, and maple syrup to a pie pan or shallow bowl. Whisk to combine.
Heat a large cast-iron skillet (or griddle) over medium heat. Heat for about 4-5 minutes to preheat the pan (for cast iron or stainless steel only).
Place 2 slices of bread into the egg mixture, letting the bread soak up the liquid for 10-15 seconds per side.
Add 1 tablespoon of butter (or oil) to the hot skillet, and swirl to melt.
Transfer the dipped slices of bread to the pre-heated skillet. Working in batches, cook for 2-3 minutes per side, or until golden brown and slightly crisp around the edges. Note: When using a cast-iron skillet, you may need to reduce the heat as the bread cooks to prevent burning, as cast iron tends to get “hotter” as the cooking time progresses. Repeat until all of the bread slices are soaked in the custard mixture, then cooked in the skillet until golden brown.
Serve with additional butter, maple syrup, fresh fruit, and/or powdered sugar.