Grease a 9x13 baking dish with butter or cooking spray. Place the sliced bread in the baking dish, overlapping only if necessary.
In a large mixing bowl, combine the eggs, milk, caramel topping, vanilla, and cinnamon. Whisk well and pour over the bread.
Cover the baking dish with plastic wrap and refrigerate overnight, or for at least 8 hours.
The next morning, bring the casserole out of the refrigerator while you preheat the oven to 350 F. Drizzle the melted butter over the bread. Bake for 45 minutes or until cooked through.