Prepare the Beef: Pat the chuck roast dry with paper towels. This is a vital step for encouraging browning. Season generously on all sides with the black pepper and garlic powder. Don't add salt yet, as the seasoning packets are quite salty.

Sear the Roast (Optional but Recommended): Heat the olive oil in a large, heavy-based frying pan over a medium-high heat until it shimmers. Sear the roast for 3-4 minutes per side, until a deep, mahogany-brown crust forms. You should hear a satisfying sizzle. This step builds a deep, savoury flavour foundation. Transfer the roast to the slow cooker.

Layer the Flavours: Sprinkle the dry au jus mix and ranch dressing mix evenly over the top of the roast. Place the pepperoncini peppers around the meat. Pour the pepperoncini brine and the beef stock into the slow cooker, being careful not to wash the seasoning off the meat. Dot the top of the roast with the butter pieces.

Slow Cook: Cover the slow cooker with the lid. Cook on the LOW setting for 8 hours, or on HIGH for 4-5 hours. The meat is ready when it is fork-tender and shreds easily. You'll know it's done when the aroma fills your kitchen – a rich, savoury scent with a hint of tang from the peppers.

Shred the Meat: Using two forks, carefully shred the roast directly in the slow cooker. The meat will be incredibly tender and will pull apart with almost no resistance. You'll see the beautiful, juicy strands separate.

Thicken the Gravy (If Desired): If you prefer a thicker gravy, remove about 120ml (½ cup) of the cooking liquid from the slow cooker. Whisk the cornflour slurry into this liquid until smooth, then pour the mixture back into the slow cooker. Stir gently and let it cook on HIGH for 15-20 minutes, until the gravy has thickened to your liking. You'll see it become glossy and coat the back of a spoon.

Rest and Serve: Turn off the slow cooker and let the roast sit for 10-15 minutes before serving. This allows the juices to redistribute. The final dish will have a rich, dark gravy, tender shreds of beef, and a wonderfully complex flavour.