Trim any fat from the chicken breasts and place into the bottom of a 6-8 quart slow cooker. Sprinkle the au jus packet and ranch seasoning evenly over the chicken. Pour the pepperoncini juice on top then add 8-10 whole peppers. Place the cubed butter on top. Cover and cook on LOW for 5-6 hours or HIGH for 3-4 hours. Remember that each slow cooker runs differently. Once the chicken reaches an internal temperature of 165°F, it is done. Once done, shred the chicken and serve meat and gravy over mashed potatoes, rice, noodles, cauliflower rice, etc.