01 - 
                Peel and slice all onions into thin rings. Mince the garlic cloves.
              
              
              
                02 - 
                Set the slow cooker to high. Add butter, sliced onions, minced garlic, brown sugar, and balsamic vinegar. Stir, cover, and cook for 20–30 minutes until onions begin to soften and develop a golden color. Alternatively, sauté the onions in a skillet over medium heat for 10 minutes before transferring.
              
              
              
                03 - 
                Dry the chuck roast thoroughly with paper towels. Season both sides with salt and pepper. Heat olive oil in a skillet over medium-high heat and sear the roast for 2–3 minutes per side until deeply browned. This step is optional but enhances flavor.
              
              
              
                04 - 
                Nestle the seared or raw roast over the caramelized onions in the slow cooker. Sprinkle thyme and bay leaves across the contents.
              
              
              
                05 - 
                Pour beef broth, white wine, and Worcestershire sauce into the slow cooker. Ensure the roast is at least partially submerged, adding more broth if necessary.
              
              
              
                06 - 
                Set the slow cooker to low and cook for 8–9 hours, or on high for 5–6 hours, until the roast is fork-tender and easily shreds. Begin checking for doneness after 7 hours.
              
              
              
                07 - 
                Transfer the cooked beef to a platter and tent loosely with foil. Skim excess fat from the cooking liquid. Mix cornstarch with cold water, then stir into the slow cooker. Cook uncovered on high for 10–15 minutes, stirring occasionally, until the gravy thickens.
              
              
              
                08 - 
                Allow the roast to rest for 10 minutes before slicing or shredding. Return meat to the slow cooker and coat generously with the onion gravy. Sprinkle with grated cheese and chopped parsley. Serve hot directly from the slow cooker or arrange on a serving dish.