Slice onions thinly, about ¼ inch thick. Heat olive oil in a large Dutch oven over medium heat. Add onions and cook until golden brown and caramelized, about 30 to 40 minutes.

Season beef chuck roast generously with salt and freshly cracked pepper. Remove caramelized onions and set aside. Sear the roast in the same pot for about 4-5 minutes on each side until a rich crust forms.

Return caramelized onions to pot, add beef broth, and bring to a simmer. Cover and transfer to a preheated oven at 300°F. Slow-cook for 3 to 4 hours or until meat is tender.

In the final 30 minutes, sprinkle a layer of Gruyère cheese over the roast and return to the oven uncovered to melt.

Remove pot from oven and let the roast rest for at least 15 minutes before slicing. Serve with onion gravy and enjoy.