Spray a 6 or 7 quart slow cooker insert with cooking spray. Set aside.
Whisk together beef broth, browning sauce, thyme and rosemary in a medium bowl. Set aside.
Combine salt, pepper and garlic powder in a small bowl. Season roast by rubbing it in all sides of roast.
Heat olive oil in a large skillet over medium high heat. Brown roast on all sides (about a minute on each side).
Place carrots, onion, celery, potatoes and bay leaf in prepared slow cooker insert. Pour broth mixture over vegetables.
Place browned roast on top of vegetables.
Cover and cook on low heat (preferred) for 8 to 10 hours or on high heat for 5 to 6 hours, or until beef and vegetables are tender.
Carefully transfer roast and vegetables to a serving platter. Remove and discard bay leaf.
Combine cornstarch and water in a small bowl. Pour into your slow cooker and stir to combine. Cover and cook on high heat for approximately 5 minutes, or until thickened.
Serve garnished with chopped fresh parsley, if desired.