01 - Preheat oven to 325°F.
02 - Pat the beef dry and season with salt and pepper.
03 - Heat olive oil in a large Dutch oven over medium-high heat. Sear the roast on all sides until deeply browned, about 4–5 minutes per side. Remove and set aside.
04 - Reduce heat to medium. Add butter and sliced onions. Cook, stirring often, until onions are deeply caramelized, about 20–25 minutes.
05 - Stir in garlic and cook for 1 minute. Sprinkle flour over onions and cook, stirring, for 2 minutes.
06 - Deglaze the pot with white wine, scraping up any browned bits. Cook until wine is reduced by half, about 2 minutes.
07 - Return roast to the pot. Add beef broth, Worcestershire sauce, thyme, and bay leaf. Arrange carrots and potatoes around the roast. Bring to a simmer, cover, and transfer to the oven.
08 - Braise for 2.5–3 hours, or until beef is fork-tender.
09 - Remove roast and vegetables. Discard thyme stems and bay leaf. Skim excess fat from the sauce, then simmer on the stovetop if needed to thicken further.
10 - For a classic French onion finish, sprinkle Gruyère cheese over the roast and broil until melted and bubbly.
11 - Slice or shred the beef and serve with vegetables and gravy. Garnish with parsley.