01 - 
                Preheat oven to 300°F (150°C) and adjust rack to lower middle position.
              
              
              
                02 - 
                Pat chuck roast dry, season generously with salt and black pepper. Heat olive oil in a large oven-safe Dutch oven over medium-high heat. Sear the roast until deeply browned on all sides, about 5 minutes per side. Transfer to a plate.
              
              
              
                03 - 
                Lower heat to medium. Add unsalted butter to the same pot, then add sliced onions. Cook, stirring frequently, until onions are deep golden brown, approximately 25-30 minutes.
              
              
              
                04 - 
                Stir in minced garlic and cook for 1 minute. Pour in white grape juice, scraping up any browned bits. Allow to simmer and reduce by half, about 3-4 minutes.
              
              
              
                05 - 
                Pour in beef broth, add rosemary and thyme sprigs. Return seared roast to the pot, nestling it into the onions and broth.
              
              
              
                06 - 
                Cover with a tight-fitting lid and transfer to the oven. Braise for 3 1/2 hours, or until beef is fork-tender.
              
              
              
                07 - 
                Remove pot from oven. Use two forks to shred the beef in the cooking liquid. Sprinkle Gruyere cheese over the beef and return uncovered to oven for 8-10 minutes, until cheese is fully melted.