Preheat the oven: Set to 375°F (190°C).
Lightly grease a 9-inch baking dish or similar.
Soften the cream cheese: Let it sit at room temp for 15–20 minutes, or microwave in short bursts until spreadable.
Make the base: In a bowl, stir together cream cheese, buffalo sauce, and ranch (or blue cheese dressing) until smooth.
Season: Mix in garlic powder, onion powder, and a few cracks of black pepper.
Add chicken: Fold in shredded chicken until evenly coated.
Cheese it up: Stir in half the cheddar and half the Monterey Jack. Spread mixture into the baking dish.
Top and bake: Sprinkle the remaining cheeses over the top. Add crumbled blue cheese if using.
Bake for 18–22 minutes, until hot and bubbly around the edges.
Brown the top (optional): Broil for 1–2 minutes to lightly brown the cheese. Watch closely.
Finish and serve: Let rest 5 minutes. Sprinkle with green onions.
Serve warm with your favorite dippers.