Whisk eggs, milk, and salt in a medium bowl until smooth; set aside.
Melt butter in a large frying pan over medium-high heat. When butter foams, add bread and fry, stirring frequently, until golden brown and toasted on all sides, about 3 to 4 minutes.
Remove the pan from heat and pour egg mixture over bread. Stir until bread is coated, then return the pan to medium heat. Cook, stirring constantly, until egg is cooked through, about 3 minutes. Serve immediately with cinnamon sugar or maple syrup.