In a large Dutch oven, heat the butter over medium-high heat. Add the bacon and ham and cook until caramelized and light brown, about 15 minutes. Add the ground meats and cook over high heat until well browned, stirring constantly, about 20 minutes.
Add the onions, carrots, celery, and mushrooms and cook until soft, about 10 minutes. Add the garlic, cloves and nutmeg to the pan and cook for 2 minutes. Add tomato paste and cook for 2 minutes. Add the wine and stock and simmer over medium-high heat until sauce is thickened and flavorful, about 45 minutes to 1 hour. Season with salt and pepper.
Add the chicken livers to the pot and cook 5 minutes. Stir in the cream and parsley, and adjust seasoning, if necessary. Set aside until ready to assemble lasagna.
Yield: about 3 quarts