01 -
Coat the interior of a large slow cooker with non-stick cooking spray or insert a slow cooker liner.
02 -
Spread diced onion evenly along the bottom of the slow cooker, then arrange chicken breasts over the onions.
03 -
Evenly disperse the au jus gravy mix and ranch dressing mix over the chicken breasts.
04 -
Place pepperoncini peppers around the chicken and lay the sliced butter on top.
05 -
Pour the pepperoncini juice evenly over all ingredients.
06 -
Cover and cook on high for 4–5 hours or on low for 6–7 hours, until the chicken is tender and easily shredded.