Beef Bolognese with Linguine

In a stockpot, cook half the beef over medium heat until no longer pink, breaking into crumbles, 8-10 minutes. Remove beef with a slotted spoon; set aside. Pour off drippings. Repeat with remaining beef., In the same stockpot, heat oil over medium heat. Add onions, carrots and celery; cook and stir until tender. Stir in 1 cup tomato paste; cook and stir 3 minutes longer. Add garlic, seasonings and beef., Stir in wine. Bring to a boil; cook until almost evaporated. Add tomatoes, stock and bay leaves; return to a boil. Reduce heat; simmer, uncovered, until desired consistency, about 3 hours, stirring in milk halfway through cooking., Remove bay leaves. Stir in cheese and remaining tomato paste; heat through. Serve with linguine and, if desired, additional cheese.