Pat the beef chuck roast dry with paper towels. Season with salt, black pepper, garlic powder, and onion powder.

Heat olive oil in a skillet over medium-high heat. Sear the beef roast on all sides for 3-4 minutes.

Transfer the roast to the slow cooker. Arrange sliced yellow onion around it, sprinkle minced garlic on top.

Wash and halve the baby potatoes, peel and cut the carrots into chunks. Place around the beef.

In a bowl, combine beef broth, balsamic vinegar, brown sugar, Worcestershire sauce, soy sauce, Dijon mustard, thyme, and rosemary. Whisk until the brown sugar is mostly dissolved.

Pour the sauce evenly over the beef and vegetables in the slow cooker.

Cover and cook on LOW for 8-9 hours without lifting the lid.

Transfer the cooked beef to a cutting board. Check that the vegetables are tender.

Remove excess fat from the cooking liquid. Mix cornstarch with cold water, then stir into the sauce.

Cover and cook on HIGH for 15-20 minutes until thickened.

Shred the beef into bite-sized pieces and return to the slow cooker.

Soak the beef in the sauce for 5 minutes. Garnish with chopped parsley and serve.