Heat olive oil in a large skillet over medium-high heat.
Add beef cubes in batches and brown on all sides, about 5 minutes per batch. Transfer browned beef to the slow cooker.
In the same skillet, add chopped onion, carrots, and celery. Cook until softened, about 5 minutes.
Add minced garlic and cook for 1 minute until fragrant.
Pour in the red wine to deglaze the skillet, scraping up any browned bits. Let the wine reduce by half, about 3 minutes.
Transfer the vegetable and wine mixture to the slow cooker with the beef.
Add crushed tomatoes, tomato paste, beef broth, dried oregano, dried thyme, bay leaves, salt, and pepper to the slow cooker. Stir to combine.
Cover and cook on low for 6 hours, or until the beef is very tender and the sauce is thickened.
About 15 minutes before serving, bring a large pot of salted water to a boil.
Cook pappardelle pasta according to package instructions until al dente.
Drain pasta and divide among serving plates.
Remove bay leaves from the ragu and stir the sauce to shred any large pieces of beef.
Spoon the beef ragu generously over the pappardelle.
Garnish with chopped fresh parsley and freshly grated Parmesan cheese.
Serve immediately.