Place the chicken breasts in the slow cooker in a single layer.
Pour the pepperoncini juice over the chicken.
Sprinkle the au jus mix and ranch seasoning evenly over the chicken.
Add the pepperoncini peppers around the chicken.
Place the butter slices on top.
Cover and cook on high for 3.5 hours or low for 6-8 hours.
Once done, use two forks to shred the chicken directly in the slow cooker.
Stir well to coat the shredded chicken in the buttery, tangy sauce.
Serve hot over mashed potatoes, rice, in sandwiches, or tacos.