Place chicken in a 1-1/2- or 3-qt. slow cooker. Top with wing sauce, butter and ranch dressing mix. Cook, covered, on low until thermometer inserted in chicken reads 165°, 2-1/2 to 3 hours. , Remove chicken; shred with 2 forks. Reserve 1/3 cup cooking juices; discard remaining juices. Return chicken and reserved juices to slow cooker; heat through., Place romaine salad mix in a serving dish. Top with shredded chicken, carrots, avocado and blue cheese; drizzle with blue cheese dressing. Serve immediately.