Pat the beef chuck roast dry with paper towels and season with salt and pepper.

Heat olive oil in a skillet over medium-high heat, sear the roast for 3–4 minutes on each side.

Transfer the seared roast to the slow cooker.

Sauté chopped onion in the same skillet for 2–3 minutes, then add garlic and cook for an additional minute.

Add the sautéed onion and garlic to the slow cooker over the roast.

Layer carrots and potatoes around the roast in the slow cooker. Add mushrooms if using.

Mix beef broth, Worcestershire sauce, thyme, rosemary, and bay leaves in a bowl, then pour over the roast and vegetables.

Cover and cook on low for 8–10 hours or high for 4–5 hours.

Remove the roast and vegetables, let the roast rest for at least 10 minutes before slicing.

Serve with vegetables and cooking liquid.