Preheat your oven to 325°F (163°C). Pat the beef chuck roast dry with paper towels and season generously on all sides with salt and black pepper.

Heat the olive oil in a large Dutch oven over medium-high heat. Once the oil is shimmering, add the beef and sear deeply until a dark brown crust forms, about 4-5 minutes per side. Remove the beef and set aside on a plate.

Reduce the heat to medium. Add the sliced onions to the pot and sauté for 5-7 minutes until softened and starting to caramelize. Stir in the minced garlic and cook for another minute until fragrant.

Pour in the red wine to deglaze the pot, scraping up any browned bits stuck to the bottom with a wooden spoon. Allow the wine to simmer for 2-3 minutes to reduce slightly.

Stir in the crushed tomatoes, beef broth, and fresh thyme sprigs. Return the seared beef (and any accumulated juices) to the pot. The liquid should come about halfway up the sides of the meat.

Cover the Dutch oven with a tight-fitting lid and transfer it to the preheated oven. Braise for 3 to 3.5 hours, or until the beef is fork-tender and pulls apart easily.

Remove the pot from the oven. Discard the thyme stems. Skim off any excess fat from the surface of the sauce if desired.

Using two forks, shred the beef into large chunks directly in the sauce. Taste and adjust seasoning with additional salt or pepper if needed.

Serve the warm braised beef and rich tomato onion gravy ladled generously over cooked pappardelle pasta. Garnish with fresh thyme leaves.