Slice muffins vertically into thin slices, approx. 1/4" thick. Place muffin slices on a wire rack set over a baking sheet, and place under the broiler. Keep a close eye on the slices as they can go from perfectly crispy to waaaay too crispy in a short amount of time. Once edges are dark brown and top side of slices are crisp, flip and let other side broil until they are to the same doneness as the first side. Set aside to cool.