Preheat the oven to 325°F.
Season the roast generously on all sides with about 2 tablespoons of the Blues Hog Bold & Beefy Seasoning.
Heat the olive oil in a large Dutch oven over medium-high heat. Sear the roast for 3–4 minutes per side until golden brown, then remove and set aside.
Reduce the heat to medium and add the butter and sliced onions to the same pot. Cook for 15–20 minutes, stirring occasionally, until the onions are deep golden brown.
Stir in the garlic, tomato paste, and remaining Blues Hog seasoning and cook for 1 minute.
Pour in the white wine and scrape up all the browned bits from the bottom of the pot. Simmer for 2–3 minutes.
Stir in the beef broth, Worcestershire sauce, and balsamic vinegar.
Return the roast to the pot, nestling it into the onions. Add the thyme, rosemary, and bay leaf, and spoon some of the onions over the top of the roast.
Cover and bake for 3–4 hours, until the roast is fork-tender and pulls apart easily. Check halfway through and add a splash of broth if the liquid is getting low.
Remove from the oven and discard the herb stems and bay leaf.
Optional: To thicken the gravy, transfer the roast to a plate, set the Dutch oven on the stovetop over medium heat, and stir in the cornstarch slurry. Simmer until thickened.
Return the roast to the gravy and gently shred it into large pieces.
Optional: Sprinkle the Gruyère over the roast and broil uncovered for 1–2 minutes until melted and bubbly (only if your Dutch oven is broiler-safe).
Garnish with fresh parsley and serve.