Preheat oven to 350°F (175°C).
In a large mixing bowl, combine the shredded chicken, Greek yogurt, buffalo hot sauce, garlic powder, and dried ranch seasoning.
Stir until all ingredients are thoroughly incorporated and the chicken is evenly coated.
Transfer the mixture into an 8x8 inch oven-safe baking dish and spread into an even layer.
Sprinkle the shredded mozzarella cheese over the top of the mixture.
Bake for 20 minutes or until the dip is heated through and the cheese has melted and started to bubble.
Remove from the oven and garnish with chopped green onions before serving.