Prepare the batter: In a mixing bowl, whisk together 4 eggs, 1 cup milk, 1 tsp vanilla extract (if using), ½ tsp cinnamon, and a pinch of salt until well combined.
Preheat the pan: Heat a skillet or griddle over medium heat. Add butter or oil and wait until it sizzles.
Soak the bread: Dip each slice of bread into the egg mixture, allowing it to soak for 15-30 seconds per side. (Thick artisan slices can handle a bit more time; don't oversoak or bread will become soggy.)
Cook the French toast: Place soaked bread slices in the preheated pan, being careful not to crowd them. Cook for 2-3 minutes per side, or until golden brown and slightly crispy on the outside.
Keep warm (if cooking in batches): Transfer cooked slices to a 250°F oven to keep warm while you finish cooking the rest.
Serve: Top with your choice of toppings: maple syrup, fresh fruit, nut butter, yogurt, whipped cream, or get creative with your own combinations.