Season the chuck roast on all sides with salt & pepper and set aside
Make caramelized onions in an oven safe dish by adding butter & onions to a pan and cooking on low until translucent, stirring every 5 minutes for about 20-25 minutes total
When onions are translucent, stir in tomato paste, Worcestershire, balsamic vinegar, and thyme
Add the chuck roast between the onions, add beef broth and garlic, cover with a lid and cook at 350°F for 3 hours (approximately 1 hour plus 30 minutes per pound)
Pull the roast out and shred using two forks, stir so the onions and broth coat the meat, taste and adjust salt and acidity
Put back in the oven at 425°F for 30-45 minutes
Remove, top with finely shredded cheese, put back in the oven to broil for 2 minutes
Finish with finely chopped parsley for color and serve as is, over mashed potatoes, cauliflower mash, rice, or as a sandwich in toasted bread
