Preheat your oven to 350°F (175°C).
In a large mixing bowl, combine the shredded chicken, softened cream cheese, ranch dressing, and buffalo sauce. Mix until well combined.
Stir in the shredded cheddar cheese and blue cheese (if using) until evenly distributed.
Transfer the mixture to a baking dish and spread it out evenly.
Bake in the preheated oven for 20-25 minutes, or until the dip is hot and bubbly.
Remove from the oven and let it cool for a few minutes. Garnish with chopped green onions before serving.
Serve warm with tortilla chips or celery sticks for dipping.