Preheat & Prep: Preheat the oven to 375°F. Season the chuck roast generously with salt, pepper, paprika, and thyme.
Roast the Beef: Place the roast in a Dutch oven or deep baking dish. Add the quartered onion, vegetable stock, and Worcestershire sauce. Cover tightly with a lid or foil and roast for 30 minutes at 375°F.
Slow Cook: Reduce the oven temperature to 325°F and continue roasting for 3 to 3.5 hours, or until the beef is tender and easily shreddable. (once the roast comes out, if you are making homemade biscuits, get started on those - the link is below).
Shred & Strain: Remove the roast from the pan and shred the beef. Strain the pan drippings into a saucepan, discarding the onions and any solids.
Make the Au Jus: Simmer the strained drippings over medium heat for about 5 minutes to reduce slightly. Taste and adjust seasoning with salt and pepper if needed.
Thicken the Gravy (Optional): In a small bowl, whisk together 2 Tbsp cornstarch and 2 Tbsp water to create a slurry. Slowly add to the simmering drippings, whisking constantly, until the desired thickness is reached.
Bake the Biscuits: Prepare biscuits according to your chosen recipe or bake the refrigerated biscuit dough as directed on the package.
Assemble & Serve: Split the warm biscuits, pile on the shredded beef, and drizzle with gravy. Serve with a side of au jus for dipping.