Spray a 6 quart or 8 quart slow cooker with spray cooking oil. Place the chuck roast into the slow cooker.: The initial hiss of the spray and the cool metal meeting the raw beef sets the scene. You should notice the roast sitting snugly in the cooker, its surface slightly tacky where seasoning will adhere. This containment ensures even heat distribution. A frequent misstep is using a cooker that's too small, which crowds the meat and prevents proper circulation of heat and liquids. If the roast teeters, reposition it so the thickest part is centered.
Sprinkle the ranch and brown gravy seasoning over the top of the roast. Slice the butter into pieces. Place the butter pieces on top of the roast. Add the pepperoncini peppers around the roast. Pour the beef broth and the water around the edges of the roast.: When the powdered seasonings meet the roast, you'll see them cling and begin to darken slightly as they absorb surface moisture. The sliced butter will sit like little yellow islands that melt steadily, releasing a rich scent. Nestling the pepperoncini peppers around the meat lets their briny liquid mingle with the broth. Pour liquids at the edges to avoid washing seasonings off the top. A common error here is dumping everything in a heap, which can prevent even seasoning. Take a moment to space the butter and peppers evenly.
Cover the slow cooker and cook on low for 8-10 hours, or until the roast shreds easily. The roast needs to be at least 145 degrees to be safe to eat, but will taste most tender when registering over 190 degrees on a meat thermometer. See notes.: As the cooker warms, you will notice a slow perfume of beef and tang rising, and gentle bubbling at the edges. Low heat allows connective tissue to break down without drying the muscle fibers. The surface color will deepen to a caramelized brown and the liquid will reduce to a glossy sauce. Avoid the temptation to increase heat to speed things up, because that often yields a tougher texture. If you must shorten time, use high for 4 to 6 hours but watch for dryness.
Shred the meat with two forks turned backward in the crock pot, allowing the meat to soak up the juices. Remove any large pieces of fat or chewy connective pieces as you shred.: When you pull the forks through, the beef should part easily and release clouds of savory steam. The aroma becomes more concentrated as you shred, and each strand will glisten from the sauce. Use forks with reversed tines to maximize shredding control. Watch for large pockets of fat or sinew, and trim them away as you encounter them to improve mouthfeel. A common slip is over shredding into a mush, so stop when you still see defined strands.
Serve warm over your favorite mashed potatoes, over egg noodles or on a bun. Top with extra pepperoncini peppers if desired, then enjoy!: The final plate will show tender, glossy shreds resting on a bed that soaks up the juices, releasing savory steam and a buttery tang. The contrast between the meat and the starch is crucial for balance, and the extra pepperoncini peppers add pops of acidity with each bite. A usual mistake is serving the roast cold or without enough sauce, which makes it seem dry; always spoon some braising liquid over the meat when plating.