01 - Pat the beef roast dry with paper towels. Season all sides generously with salt and pepper.
02 - Heat a large skillet over medium-high heat. Sear the roast on all sides until well-browned, about 3-4 minutes per side. Transfer to the slow cooker.
03 - Place carrots, potatoes, celery, and onion around and beneath the roast in the slow cooker.
04 - Whisk together beef broth, Worcestershire sauce, tomato paste if using, thyme, rosemary, and garlic. Pour the mixture over the beef and vegetables. Add bay leaves.
05 - Cover and cook on LOW for 8 hours, or until the beef pulls apart easily with a fork and vegetables are tender.
06 - Discard bay leaves. Shred the beef using two forks. Serve hot with vegetables and cooking juices.