Season the chuck roast generously with salt, pepper, rosemary, and thyme on all sides.
In a large skillet, heat olive oil over medium-high heat. Sear the roast for 3-4 minutes per side until deeply browned.
Place the onion, garlic, carrots, and potatoes in the bottom of a 6-quart slow cooker.
Position the seared roast on top of the vegetables.
In a small bowl, whisk together the beef broth, balsamic vinegar, and Worcestershire sauce.
Pour the liquid mixture over the beef and vegetables.
Cover and cook on the LOW setting for 8 to 10 hours until the beef is fork-tender.
Remove the roast and vegetables carefully and place them on a large serving platter.
Skim any excess fat from the liquid remaining in the pot.
Pour a bit of the natural jus over the meat and garnish with fresh chopped parsley before serving.