In the chicken fillet, make an incision in the form of a “pocket”, then lightly beat off.
Fill the pocket 1/3 with ketchup.
Put a strip of hard cheese inside.
Secure the incision with a skewer, season with salt and pepper.
Roll in flour, shake off excess.
Dip a chicken egg beaten with a pinch of salt.
Immediately roll on both sides in pre-diced potatoes, fry on both sides in a frying pan heated with vegetable oil. Remove from the heat, cover with foil so that the meat comes to readiness, or bring it to full readiness in the oven.