Preheat your oven to 350°F (175°C).
Shred the chicken into bite-sized pieces if using leftover chicken, or cook it until fully cooked and then shred.
In a large mixing bowl, combine cream cheese and sour cream until smooth, then fold in cheddar and mozzarella cheeses.
Add shredded chicken, buffalo sauce, garlic powder, and chopped green onions to the cheese mixture and stir until well combined.
Transfer the mixture to an oven-safe baking dish and spread evenly.
Bake for about 20-25 minutes until bubbly and slightly browned on top.
Let it cool for a minute before serving, garnished with additional green onions if desired.