Pat the chuck roast dry with paper towels.
Season all sides with salt, black pepper, garlic powder, thyme, rosemary, and paprika.
Heat olive oil in a large skillet over medium-high heat.
Sear the roast for 3–4 minutes per side, until deeply browned.
Transfer the roast to the slow cooker.
Arrange the potatoes, carrots, onion, and garlic around the roast.
In a bowl, whisk together beef broth, Worcestershire sauce, tomato paste, thyme, and rosemary.
Pour the mixture into the slow cooker around the roast.
Add the bay leaves.
Cover with the lid.
Cook on LOW for 8–9 hours or HIGH for 4–5 hours.
Cook until the roast is extremely tender and easily pulls apart with a fork.
Carefully transfer the roast and vegetables to a serving platter.
Remove and discard the bay leaves.
Pour some of the cooking liquid into a saucepan.
In a small bowl, whisk together cornstarch and cold water.
Bring the cooking liquid to a gentle simmer.
Gradually whisk in the cornstarch slurry.
Cook for 2–3 minutes, stirring continuously, until the gravy thickens.
Taste and adjust salt and pepper.
Slice or shred the roast and serve with the cooked vegetables.
Spoon the homemade gravy over the beef and garnish with fresh parsley.