Season the beef chuck roast on all sides with the salt and black pepper.
Arrange the carrots, potatoes, parsnips, and onion in an even layer in the bottom of the slow cooker.
Place the seasoned roast on top of the vegetables.
Stir together the beef broth, Worcestershire sauce, garlic, rosemary, thyme, and bay leaves in a bowl, then pour the mixture over the roast.
Cover the slow cooker and cook on low for 8 hours, until the beef is fork-tender.
Remove and discard the bay leaves before serving the roast with the vegetables and broth.