Dab both sides of chuck roast with a paper towel, cut into 6 even pieces, and generously salt and pepper all sides. (I use almost a full tablespoon salt and about 1 teaspoon pepper.)
Heat 1 and 1/2 tablespoons of the olive oil in a large Dutch oven (or oven-safe heavy-bottomed pot) over medium-high heat. Brown pieces on all sides for 3 minutes. To get a good sear, don’t overcrowd the meat; you can sear in batches if needed). Once meat is nicely seared with a good crust, and place pieces in the slow cooker. Use a 5-quart or larger slow cooker.
In the Dutch oven, turn heat down to medium-low and add remaining 2 tablespoons of olive oil. From the mirepoix, add onion and sauté for 2 minutes. Next, add carrots and celery and sauté, stirring occasionally, 5–8 minutes. Add garlic and sauté for 30 seconds.
Turn heat to high, add red wine or beef stock, and scrape up any browned bits. Stir and simmer 3 minutes, then pour stock and veggie mixture into the slow cooker. While the veggies are simmering, add everything else to the slow cooker: crushed tomatoes, tomato paste, dried thyme, dried basil, dried oregano, bay leaves, and beef bouillon cube (see note 1).
Cover cook on low heat (high is not recommended) for 6–8 hours (The meat is perfect right around 7–7.5 hours—tested in both my slow cookers.) Remove beef, discarding any gristle or fat, and shred with 2 forks, then return to slow cooker.
Adjust meat sauce’s seasoning to taste with salt and pepper. Cover and place on warm or cover and store in the fridge overnight if you’re making ahead of time.
When ready to serve, bring a large pot of water to a boil. Add a tablespoon of salt, then add the pappardelle pasta (see note 2). Cook according to package instructions but do not drain! Right before pasta is done cooking, remove 1 cup of pasta water.
Meanwhile, place about half the meat sauce in a very large pan. Put over high heat. Once pasta is cooked, add it straight to the pan. Toss pasta with meat sauce, slowly adding in the reserved pasta water as needed. (I’ll use anywhere from 1/2 cup to the full cup.) If serving a large group, use all the sauce.
Toss everything until you have a thick sauce that coats the pasta and the pasta water has evaporated. Serve immediately topped with fresh parsley as desired and plenty of freshly grated Parmesan cheese.
Notes
Note 1: Here are the exact beef bouillon cubes I use. These are dual strength, meaning you’ll need 2 teaspoons of bouillon powder or 2 smaller cubes.Note 2: This dish makes a lot of food. I generally make it for 2 meals unless I’m serving a crowd. To have 2 meals, cook half the pasta and toss with half the meat sauce. Reserve the rest of the (uncooked) pasta and the rest of the meat sauce to prepare later on in the week.Storage: Beef Ragu can be stored in the fridge for up to 4–5 days. If possible, keep sauce and pasta separate. To freeze, use a gallon-sized bag to freeze the sauce for up to 3 months. Avoid freezing pasta; cook it fresh when you’re ready to serve.