Place the chicken breasts in a 4 quart slow cooker. Salt and pepper the chicken.
In a medium bowl, combine the hot sauce, mustard, and Ranch seasoning. Pour it over the chicken.
Set the slow cooker to high, and cook for 4 hours.
After 4 hours, remove the chicken to a plate and shred it. Add the butter to the crock pot and stir so that it melts into the sauce. Add the chicken to the crock pot again and stir to coat with the sauce.
Serve immediately or let the shredded chicken hang out in the crock pot on low for another hour.
Note: We like to eat our Buffalo Chicken taco-style. But you do you. Eat it however feels right. It's great on a baked potato, or on its own as well. However you choose to eat it, let me recommend a little drizzle of Ranch dressing to temper the heat.