Place roast in slow cooker. Pour packages of ranch and au jus on top of roast. Place stick of butter on top and arrange pepperoncinis around butter.
Cover with lid and cook on low for 8 to 10 hours or high for 4 to 5 hours.
Shred or slice and serve.
The drippings are wonderful served poured over the meat. If you would like a little thicker gravy add 2 tablespoons of corn starch to ¼ cup water and stir with a fork or whisk. Pour back into slow cooker and stir.