Preheat oven to 350°F (175°C). Lightly grease a 9-inch baking dish.
In a large mixing bowl, combine the softened cream cheese, shredded chicken, buffalo sauce, cheddar cheese, mozzarella cheese, and ranch dressing. Stir until well blended.
Transfer the mixture to the prepared baking dish and spread evenly.
Bake in the preheated oven for 25–30 minutes, or until the dip is hot and bubbly and the top is lightly golden.
Remove from oven and let cool for 5 minutes. Sprinkle with blue cheese crumbles and green onions if desired before serving.
Notes
Serve warm with tortilla chips, celery sticks, or crackers.