Sweat the onions with the parsley until soft but not colored. Meanwhile in a mixer bowl add the beef, pork, veal, egg, grated parmesan,cumin powder, nutmeg, ricotta, bread crumbs, salt and pepper.
Mix well until all is combined. Add the onions and parsley mixture, cognac and mix again.
Cover a cutting board with a rectangular piece of saran wrap. Scoop the meatloaf mixture in the middle of the board and with wet hands form an even rectangle about 10x15 inches. Layer the sage, fontina and lemon peel, forming a strip in the center.
Using the saran wrap to help you, roll the meatloaf and seal all the edges forming a cylinder.
Discard the saran wrap. Place the meatloaf in lined oven dish and cover with the pancetta slices overlapping them slightly. Cook in a preheated oven for about 45 minutes.
You can make the meatloaf and freeze it before cooking it.