It’s a lot like a saltimbocca, but made with chicken cutlets instead of veal. The cutlets are layered with a butter fried sage leaf and wrapped in thin prosciutto. Then they are dipped in beaten egg, fried briefly, topped with fontina cheese, and broiled. Such a lovely presentation! Perfect for entertaining. Working in batches so that you don’t crowd the pan, dip each prosciutto-wrapped chicken cutlet in beaten egg and place it in the pan. Cook them for a couple minutes on each side, until just cooked through. Remove from the pan. Add the minced sage and cook for a minute longer. Stir in the chilled butter. Pour the sauce around the chicken cutlets to serve.