Preheat the oven to 375°F (190°C).
In a large mixing bowl, combine the softened cream cheese, ranch dressing, buffalo wing sauce, and sour cream until smooth.
Stir in the garlic powder, onion powder, and black pepper.
Fold in the shredded chicken, half of the cheddar cheese, half of the mozzarella cheese, and the green onions until evenly combined.
Transfer the mixture to a lightly greased baking dish and spread it into an even layer.
Sprinkle the remaining cheddar and mozzarella cheese over the top. Add crumbled blue cheese if using.
Bake for 20 to 25 minutes, or until the dip is hot and bubbly and the cheese is melted.
Let the dip cool for 5 minutes before serving.
Garnish with fresh parsley or sliced green onions and serve warm with your favorite dippers.