Beat the eggs, milk, vanilla, and salt together in a large bowl until cream-colored. Pour into a shallow dish. Dip the bread in the mixture, one slice at a time, until soaked.
Sweep a stick of butter around the inside of a hot oiled skillet. Fry the bread in batches over medium heat until golden brown, turning once, about 3 to 4 minutes on each side. Remove to a baking sheet in the oven to keep warm until all the slices are cooked. Serve sprinkled with cinnamon sugar and syrup.