01 - Preheat oven to 325°F.
02 - Pat the beef dry with paper towels and season generously with kosher salt and freshly ground black pepper on all sides.
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 beef from pot and set aside.
04 - Reduce heat to medium. Add butter and sliced onions to the pot. Cook, stirring frequently, until onions are deeply caramelized and golden brown, about 20–25 minutes.
05 - Stir in minced garlic and cook for 1 minute until fragrant. Sprinkle flour over the onions and cook, stirring constantly, for 2 minutes to remove raw flour taste.
06 - Pour in white wine, scraping up any browned bits from the bottom of the pot with a wooden spoon. Simmer until wine is reduced by half, about 2 minutes.
07 - Return the seared roast to the pot. Add beef broth, Worcestershire sauce, fresh thyme sprigs, and bay leaf. Arrange carrots and halved potatoes around the roast.
08 - Bring liquid to a simmer, cover tightly with lid, and transfer to preheated oven. Braise for 2.5–3 hours, or until beef is fork-tender and easily pulls apart.
09 - Remove roast and vegetables from the pot. Discard thyme stems and bay leaf. Skim excess fat from the sauce surface. Simmer sauce on stovetop over medium heat if additional thickening is desired. Optionally, sprinkle Gruyère cheese over the roast and broil until melted and bubbly.
10 - Slice or shred the beef against the grain. Arrange meat and vegetables on serving plates, ladle hot gravy over top, and garnish with chopped fresh parsley.