Heat a large skillet over medium heat. Add the ground beef and cook until it is no longer pink, breaking it up with a spoon as it browns. Drain any excess fat.
Add the onion and garlic to the skillet with the beef. Cook for 2 to 3 minutes until the onion softens.
Transfer the beef mixture to the slow cooker. Stir in the crushed tomatoes, tomato paste, oregano, basil, beef broth, salt, and pepper.
Cover and cook on low for 6 to 7 hours or on high for 3 to 4 hours until the sauce thickens and the flavors meld.
About 15 minutes before serving, cook the pappardelle in a large pot of salted boiling water according to package directions. Drain the pasta.
Spoon the ragu over the cooked pappardelle. Top with chopped parsley and grated Parmesan.