Butterfly the meat and season both sides. Place two slices of meat on each steak, spread the cheese over the top. Fold the steaks over and secure with toothpicks.
For the crumb coating
Empty the flour and breadcrumbs each into a shallow dish. Beat the egg in a deep dish. Turn the steaks in the flour in batches, shaking off the excess flour, then coat in the egg then the breadcrumbs. Press the breadcrumbs down firmly.
Heat the clarified butter in a frying pan. Reduce the heat, fry the cordon bleus over a medium heat for approx. 4 mins. on each side.