Melt butter in a saucepan and add onion, celery, carrot and pancetta. Cook over moderate heat for 6-8 minutes, stirring from time to time.
Add the mince beef, pork and oregano to saucepan. Season with salt and pepper and nutmeg. Cook for approximately 5 minutes.
Add chicken livers and cook until it changes colour.
Pour in wine, increase heat and boil over high heat for 2-3 minutes, or until wine is absorbed.
Stir in 1/2 of the milk, reduce heat and simmer for 10 minutes.
Add tomato, tomato puree, stock and Osso bucco (1 piece for entrée and 5 for main).
Partially cover the pan and leave to simmer gently over very low heat for 3-3 1/2 hours. At 2 – 2.5 hours of cooking time take out 5 pieces of Osso Bucco for main (See below).
Add more stock as needed to keep sauce moist.
5 minutes before serving stir the remaining milk into the sauce 5 minutes before serving.
Taste the sauce for seasoning and serve on al dente Tagliatelle Pasta and grated parmesan.