Heat a non-stick skillet or griddle over medium heat. Add butter and allow it to melt. Swirl the melted butter to coat the skillet.
Whisk egg and milk in a shallow bowl large enough to dip the bread. Add cinnamon and vanilla and mix again.
Dip bread in egg/milk mixture. Turn the bread over and make sure the bread has been completely submerged in the mixture. Transfer to skillet and fry until golden on both sides; about 5 minutes per side depending on the thickness of the bread. Repeat with remaining bread, adding more butter as needed.
Serve warm with butter and/or maple syrup.
Notes
You can use any type of milk you have available. I used skim milk along with about a quarter cup of half & half.