01 - Season beef chunks evenly with salt and pepper.
02 - Heat olive oil in a large skillet over medium-high heat. Brown beef chunks on all sides, about 5 minutes, then transfer to slow cooker.
03 - In the same skillet, add chopped onion, carrots, and celery. Cook for 4 to 5 minutes until softened, then add garlic and cook one more minute. Transfer vegetables to slow cooker.
04 - Pour red wine into skillet and simmer for 2 minutes, scraping browned bits from bottom. Add wine and remaining sauce ingredients—crushed tomatoes, tomato paste, beef broth, oregano, thyme, bay leaves, and red pepper flakes if using—to slow cooker. Stir to combine.
05 - Cover and cook on low for 8 hours or until beef is tender and shreds easily.
06 - Remove bay leaves. Shred beef directly in slow cooker using two forks, then stir well. Adjust seasoning to taste.
07 - About 20 minutes prior to serving, cook pappardelle according to package instructions. Drain and set aside.
08 - Spoon beef ragu over pappardelle. Garnish with grated Parmesan and fresh basil before serving.