Place the chicken breasts evenly in the base of your slow cooker.
Sprinkle the au jus gravy mix and ranch dressing mix over the chicken, ensuring even coverage.
Add the stick of salted butter on top of the seasoned chicken.
Scatter the peperoncini peppers over everything.
Cover the slow cooker and cook on low heat for 6 to 8 hours, allowing the chicken to cook in its own flavorful juices.
Once cooked, shred the chicken with two forks directly in the slow cooker and mix well.
Serve the shredded chicken warm as desired.