Preheat the oven to 325°F. Heat 2 tablespoons of olive oil in a large cast-iron Dutch oven over medium-high. Pat the chuck roast dry, then season all over with salt and pepper.

Sear the roast 3–4 minutes per side until deeply browned. Transfer to a plate and set aside.

Reduce heat to medium. Add remaining olive oil and the onion slices. Cook, covered, stirring occasionally for 12–15 minutes until soft.

Uncover and continue cooking 10 more minutes, stirring, until the onions develop deep golden color.

Stir in garlic, oregano, thyme, salt, and pepper. Cook 1–2 minutes until fragrant.

Sprinkle flour over the onions, stir to form a paste. Pour in beef broth, red wine, and Worcestershire sauce, scraping up any browned bits.

Nestle the seared roast back into the braising liquid. Cover and transfer Dutch oven to the oven.

Braise for 4 hours, or until the meat shreds easily. Remove the lid for the last 30 minutes to thicken the gravy.

Rest the meat 10 minutes, then shred and serve ladled with caramelized onion gravy over mashed potatoes or crusty bread.