In a medium bowl, whisk together the milk, eggs, sugar, butter, vanilla and cinnamon. Place the bread in a 13x9-inch baking dish; pour the milk mixture over the bread, turning to coat. Let stand 5 minutes.
Preheat the waffle iron and then coat with cooking spray (even if it's a nonstick waffle iron).
Place 4 bread slices on a hot waffle iron. Cook 3 to 5 minutes or until golden brown. Repeat the procedure with the remaining bread.