Pat roast dry and season with salt and pepper.

In a large skillet or Dutch oven, sear roast in olive oil until browned on all sides (about 3–4 minutes per side).

Remove roast and set aside. In the same pot, sauté onions and garlic until fragrant.

Add beef broth, balsamic vinegar, cranberry sauce, Worcestershire, and thyme. Stir and bring to a simmer.

Return roast to pot, add carrots around it, cover, and roast in oven at 300°F (150°C) for 3–4 hours, or until fork-tender.

Remove beef and shred. To thicken the sauce, stir in a cornstarch slurry over medium heat until thickened.

Serve roast over mashed potatoes, drizzle with sauce, and top with extra cranberries if desired.