Clean, wash and possibly halve the tomatoes. Peel garlic and press it through the garlic press. Wash the rosemary. Strip needles from the stalks. Puree canned tomatoes. Heat the fat.
Sauté garlic in it. Add tomatoes, season with salt, pepper and rosemary. Deglaze with pureed tomatoes, bring to the boil briefly and season to taste. Put tortelloni in boiling salted water and cook for about 2 minutes. Serve with sauce and ham. Sprinkle with sliced Parmesan