Coat the inside of the escalope with mustard, top with ham and alp cheese and fold together. Season with salt and pepper.
Place flour, beaten egg and breadcrumbs each on flat plates.
Dredge the escalope first in flour, then in the egg and finally in the breadcrumbs. Press firmly on the breadcrumb coating.
Fry the cordon bleu in plenty of hot cooking butter at medium heat for about 5 mins.