Preheat oven to 350ºF.
In a large bowl, mix together sour cream, mayonnaise, and ranch dressing. Add buffalo sauce and 1 cup shredded cheese. Stir again. Mix in the shredded chicken. Add ¼ cup blue cheese and ¼ cup green onions.
Stir again and transfer mixture to a 9x9 inch baking dish. Sprinkle remaining cheese on top.
Bake for 20 minutes. Sprinkle remaining blue cheese and green onions on top before serving. Serve with chips, crackers or carrots and celery.
