Warm 2 cups milk in small pot over lowest heat.
Heat 1/4 cup olive oil in a large Dutch oven over medium to medium-high heat. Add the pancetta and cook until lightly brown. Then add the chicken livers, and cook almost through. Add the onions, celery, carrots, garlic, rosemary, and bay leaves, and cook until tender, 10 minutes.
Add the ground meat and cook through breaking into pieces, but do not brown. Season with salt, pepper, nutmeg, clove, and stir in the wine and allow it to cook into the meat, 2 to 3 minutes. Add the warm milk to the meat and allow it to absorb into the meat for 1 minute. Stir in the beef stock, vegetable stock, and tomatoes. Bring to a simmer, then reduce the heat and simmer over low heat for 2 hours, stirring occasionally.
Divide the sauce in 1/2, cool, and freeze one batch. Cool and store the remainder for a make-ahead meal within the week. Alternately, cook pasta to al dente, thin the sauce a bit with a bit of starchy pasta water and toss with pasta dressed with butter to combine. Top with grated cheese and chopped celery leaves. Serve with green salad.