Prepare the Beef: Pat the chuck roast completely dry with paper towels. This is key for getting a good sear. Season it generously all over with salt and freshly ground black pepper.

Sear the Roast: Heat the olive oil in a large, heavy-based frying pan or Dutch oven over a medium-high heat. Once the oil is shimmering, carefully place the chuck roast in the pan. Sear for 4-5 minutes on each side, until a deep brown crust has formed. This process, known as the Maillard reaction, creates incredible depth of flavour. Once browned, transfer the roast to the slow cooker pot.

Sauté the Aromatics: Reduce the heat to medium. Add the quartered onions to the same pan and cook for 5-7 minutes, stirring occasionally, until they begin to soften and pick up the browned bits from the bottom of the pan. Add the smashed garlic and cook for another minute until fragrant.

Deglaze the Pan: Pour the red wine into the pan to deglaze it. Use a wooden spoon to scrape up all those lovely browned bits from the bottom. Let the wine bubble and reduce by about half, which should take 3-4 minutes.

Combine in the Slow Cooker: Pour the onion and red wine mixture over the roast in the slow cooker. Add the carrots, celery, beef stock, tomato purée, and Worcestershire sauce. Tuck the rosemary sprigs, thyme sprigs, and bay leaves in amongst the vegetables.

Cook Low and Slow: Place the lid on the slow cooker. Cook on LOW for 8-9 hours or on HIGH for 4-5 hours. I find that cooking on low yields the most tender, succulent result. The roast is done when it is easily pierced with a fork and shreds with little effort.

Rest the Meat: Carefully transfer the cooked roast and vegetables to a platter and cover loosely with foil to keep warm. Let the meat rest for at least 15 minutes before shredding or slicing. This allows the juices to redistribute, ensuring a moist result.

Make the Gravy: Strain the cooking liquid from the slow cooker into a medium saucepan, discarding the herb stems and bay leaves. Bring the liquid to a simmer over a medium heat. In a small bowl, whisk the cornflour and cold water together to create a slurry. Slowly pour the slurry into the simmering liquid, whisking constantly, until the gravy thickens to your desired consistency. Let it simmer for another 2 minutes. Season with salt and pepper to taste.

Serve: Shred or slice the beef and serve immediately, drizzled generously with the hot, rich gravy and garnished with fresh parsley.