Spray the slow cooker with nonstick spray. Pat the roast dry with a paper towel and season with salt and pepper. Place it into the slow cooker. Sprinkle the package of dry ranch seasoning and packet of Au Jus gravy mix over the top of the roast.
Cover with the lid and cook on low for 8 hours. You can also cook on high for 4-5 hours but cooking it slow is recommended for optimal tenderness and flavor. Once cooked, the meat will be fork tender. The roast should easily fall apart while you shred with two forks. Serve your Mississippi Pot Roast over mashed potatoes, rice, noodles, or with your favorite sides.