Spray a slow cooker with cooking spray. Place wings inside the slow cooker and pour 11 of the 12 ounce bottle over the chicken wings. Toss until all the wings are coated.
Cook on high for 2 hours and 30 minutes.
Preheat the broiler on high. Remove the wings from the slow cooker and place on a baking sheet with a lip (reserve excess sauce in the slow cooker). Broil on high for 5 minutes (3 minutes on middle rack and 2 minutes on top rack) or until wings are crispy and golden (but not burnt). Drizzle the remaining 1 ounce of buffalo sauce on to the broiled wings. Garnish wings with a little parlsey and serve with ranch dressing, bleu cheese dressing, and celery.