Preheat oven to 400°F (200°C).
Steam or boil cauliflower florets for 5 minutes until tender-crisp, then drain thoroughly.
In a large mixing bowl, whisk together buffalo sauce, Greek yogurt, cream cheese, garlic powder, and onion powder until smooth.
Fold the shredded chicken and drained cauliflower into the sauce mixture until evenly coated.
Transfer the mixture to a 9x9 inch baking dish and spread evenly.
Bake for 15 minutes.
Sprinkle shredded mozzarella over the top and bake for an additional 10 minutes until cheese is melted and bubbly.
Garnish with chopped green onions before serving.