Yield: 4-6 servings
Heat oil in a large heavy pot over medium-high heat. Add onions, celery, and carrots. Sauté until soft, 8-10 minutes. Add beef, veal, and pancetta; sauté, breaking up with the back of a wooden spoon, until browned, about 15 minutes. Add wine; boil 1 minute, stirring often and scraping up browned bits. Add 2 1/2 cups stock and tomato paste; stir to blend. Reduce heat to very low and gently simmer, stirring occasionally, until flavors meld. (Up to 1 1/2 hours.) Season with Old World Italian Seasoning.
Bring milk to a simmer in a small saucepan; gradually add to sauce. Cover sauce with lid slightly ajar and simmer over low heat, stirring occasionally, until milk is absorbed. (Up to 45 minutes, adding more stock by 1/4-cupfuls to thin if needed.)
Bring a large pot of water to a boil. Season with salt; add pasta and cook, stirring occasionally, until 1 minute before al dente. Drain, reserving 1/2 cup pasta water. Transfer ragù to a large skillet over medium-high heat. Add pasta and toss to coat. Stir in some of the reserved pasta water by tablespoonfuls if the sauce seems dry. Divide pasta among warm plates.
Serve with generous dusting of Parmesan on top.
More About This Recipe
DO AHEAD: Ragù can be made 2 days ahead. Pour into an uncovered container and cool until it reaches room temp, then cover and keep chilled. Reheat before continuing.