In a large bowl mix together the chicken, Buffalo sauce and ranch dressing. Stir until chicken is coated, then add celery, 1/2 cup of green onions and 1/2 Cup of each cheese. Stir until combined.
Place the mixture into a prepared 9x13 baking dish and spread it out evenly. Top with the Fritos, remaining cheese, and green onions.
Place in the oven and bake for about 15 minutes or until the cheese is completely melted.