Pat the roast dry with paper towels. No need to season (there's a lot of salt in the seasoning mixes).: Start by feeling the surface of the beef chuck roast as you pat it dry, the meat should feel tacky but not wet; removing surface moisture is the key to getting a proper sear, because moisture prevents browning and promotes steaming instead. You should hear a faint slap as the paper towel pulls away dampness, and the roast will look slightly drier and take on a matte tone. This step matters because browning creates complex Maillard flavors that will deepen the entire dish, contributing savory, slightly sweet notes that you won't get from slow cooking alone. A common mistake is rushing this step and putting damp meat into the hot oil, which results in a pale surface and weaker flavor development. If the roast is very cold, let it rest at room temperature for 10 to 15 minutes after patting to promote even searing; avoid leaving it out longer than 30 minutes to maintain food safety.
Heat olive oil in a large Dutch oven over medium-high heat. Once you can feel the heat when you hold your hand 6 inches above the pot, add the beef. Sear the beef for 5-7 minutes per side, until a crust forms and it releases easily from the pan.: When the olive oil shimmers and you can sense radiating heat, the pan is ready and will produce an audible sizzle as the meat meets the surface; that sound signals flavor forming. As the roast sears, watch for a deep mahogany color forming at the edges and a satisfying crust that releases cleanly when you lift the piece with tongs. Searing for 5 to 7 minutes per side is about building those layered flavors and locking in juices; the aroma will shift from raw to rich and roasted as sugars and proteins react. If you crowd the pan, the temperature drops and you risk steaming instead of browning, so work in batches if needed. Also avoid flipping too often, let each side develop a full crust before turning, and be patient if the meat momentarily sticks to the pan, it will release when properly browned.
Transfer beef to the slow cooker along with pepperoncini liquid (1/2 cup). Sprinkle ranch mix and au jus mix evenly over the roast. Top with butter pieces and pepperoncini peppers. No need to add any other liquid.: As you move the seared roast into the slow cooker , notice the savory steam rising and the concentrated smell of caramelized meat combining with tangy pepperoncini brine; that contrast is what makes the final jus so compelling. Distribute the ranch seasoning mix and au jus gravy mix in a thin layer so each bite absorbs seasoning during the long cook, and scatter the butter in small pats to create pockets of richness that will melt into the juices. The 1/2 cup of pepperoncini brine is a clever source of acidity and salt, removing the need for extra stock while helping to break down connective tissue slowly. An easy trap here is dumping all the seasoning in one spot, which can lead to overconcentrated bites; take a moment to sprinkle evenly across the roast for balanced flavor.
Cover and cook on low for 7–9 hours, or high for 5–7 hours, until the meat is very tender and easily shreds with 2 forks. (Low gives the best texture.): During the long simmer, you'll notice a slow, steady aroma filling the kitchen, evolving from meaty to almost buttery as fats render and the seasoning melds into the cooking liquid. The beef will gradually soften until a fork slides through the grain with almost no resistance, and the juices will deepen in color and viscosity as collagen becomes gelatin. Choosing low heat yields a finer, silkier texture because the proteins relax gently, while high heat accelerates the process but can produce slightly coarser strands. A frequent misstep is checking too often, which releases heat and lengthens cook time; resist peeking unless necessary. To test doneness, pull a small section with two forks, if it falls apart without effort you're ready. If the meat still resists, it needs more time rather than higher heat, because extended low heat will reward you with better mouthfeel.
Remove roast, shred with two forks, discarding any excess fat. Return meat to the liquid in the crockpot and gently stir. Serve over mashed potatoes or on rolls with Provolone (see note 2).: When you lift the roast out, it should feel light and give under the forks; shredding releases a warm, savory steam that smells concentrated and comforting. Pull the meat along the grain into irregular ribbons, tossing out large, unrendered fat pieces so each forkful has a balanced meat to sauce ratio. Returning the shredded beef to the cooking liquid allows it to soak up the jus and reheat evenly, creating glossy, well coated strands. Stir gently so you don't mash the meat, and watch as the juices cling to the fibers, providing both moisture and flavor. A common oversight is leaving too much solid fat in the mix, which can feel greasy; skim or discard those pieces for a cleaner finish. Serve immediately over warm mashed potatoes or pile onto toasted rolls topped with melted Provolone cheese and spoon extra jus on the side for dipping, the contrast of textures will make each bite more satisfying.