Trim off any fat or gristle from around the edges of your chop.
Now, very carefully cut the filet in half heightwise almost but not quite all the way to the bone, so that it ppens like a book.
Gently flatten each flap of the filet with a meat pounder with outward motion from the bone,, getting it as thin as you can manage without mauling it.
Season the chop generously inside and out with salt and pepper.
Filling the chop
Lay on a slice of ham and then a few slices of fontina, enough to cover one flap but leaving a perimeter around the edges.
Close the flap and then very gently pound the chop once more to seal the two flaps together.
Breading the chop
Lay out three shallow plates with flour, beaten egg and breadcrumbs.
Holding the chop with both hands and pinching the two flaps together, very gingerly dip the chop first in the flour, then the egg and finally in the breadcrumbs, making sure that it is well covered on both sides each time. Press the breadcrumbs into the meat so it adheres well.
Browning the chop
In a skillet large just enough to hold the chop, over medium-low heat vegetable oil enough to come up about 1/2 the height of your chop, along with a large knob of butter.
When the butter has completely melted and ceases bubbling, gingerly lay in the chop. Sauté until it is golden browned on one side, about 5 minutes (or possibly more for a thicker chop), then turn it and brown the other side as well for another 5 minutes or so.
Serve
Serve the chop right away, or keep warm until you're ready to serve. Sprinkle lightly with salt just before serving.