2 Tbsp. extra-virgin olive oil
1 garlic clove minced
2 medium onions, chopped
2 medium celery stalks, chopped
2 carrots, peeled, chopped
1/2 lb. ground beef (preferably lean)
1/2 lb. ground veal
3-4 pieces thinly sliced pancetta, finely chopped
1/2 cup dry red wine
3 cups beef stock or chicken stock, divided
3 Tbsp. tomato paste
salt and freshly ground black pepper
1 cup whole milk
1 lb. tagliatelle or fettuccine
Heat oil in a large heavy pot over medium-high heat. Add onions, garlic, celery, and carrots. Sauté until soft,about 10-12 minutes. Add beef, veal, and pancetta; sauté, breaking up the meat with the spoon and cook until browned, about 15 minutes. Add the wine and boil 1 minute, stirring often and scraping up browned bits from the pan. Add 2 1/2 cups stock and tomato paste; stir to blend. Reduce heat to very low and gently simmer, stirring occasionally, until flavors marry, 2 hours. Season with salt and pepper. Bring milk to a simmer in a small saucepan over low heat (or it will curdle); gradually add to sauce. Cover sauce with lid slightly ajar and simmer over low heat, stirring occasionally, until milk is absorbed, about 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 sauce seems dry. Divide pasta among warm plates. Serve with freshly grated Parmesan. Bon Appetit!