Melt the butter in a large pan, add the diced bacon and simmer, stirring, until the fat is transparent. Add the onion, carrot, and celery, and cook over a moderately low heat, stirring frequently, for 5 minutes. Add the ground meats. Raise the heat to moderate and saute briskly, stirring, until the meats are lightly browned. Stir in the chopped mushrooms, tomato puree, oregano, stock, wine, and bring to a boil. Lower the heat, cover the pan and simmer gently for 40 minutes, stirring occasionally. Add the cream or hot milk. Season to taste with salt and pepper. Bring the sauce to a boil and cook gently until the cream has blended with the other ingredients. Done.{$7e}(Original recipe for 4)