01 - Generously season beef chunks with salt and pepper on all sides.
02 - Heat a large skillet over medium-high heat. Sear beef chunks on all sides until deeply browned, about 3-4 minutes per side. Transfer browned beef to the slow cooker.
03 - In the same skillet, add onion, carrots, and celery. Sauté for 4-5 minutes until vegetables soften and begin to caramelize. Add minced garlic and cook for 1 minute until fragrant.
04 - Stir tomato paste into the vegetables and cook for 1 minute to deepen flavor. Pour in red wine, scraping up browned bits from the pan bottom. Simmer for 2 minutes until slightly reduced.
05 - Transfer vegetable mixture to the slow cooker with the beef. Add crushed tomatoes, beef broth, oregano, thyme, bay leaves, and red pepper flakes. Stir everything together until well combined.
06 - Cover and cook on low setting for 8 hours, or on high for 4-5 hours. The beef is done when it easily shreds with a fork.
07 - Remove and discard bay leaves. Using two forks, shred the beef directly in the sauce. Stir thoroughly to distribute the shredded meat throughout the ragu. Taste and adjust seasoning with additional salt and pepper if needed.
08 - Bring a large pot of salted water to boil. Cook pappardelle according to package directions until al dente. Drain, reserving a small amount of pasta water, and toss the pasta with a ladle of the ragu sauce.
09 - Portion sauced pasta onto plates or shallow bowls. Top generously with beef ragu. Garnish with chopped fresh parsley and a generous dusting of grated Parmesan cheese.