Preheat your oven to 375°F.
Cut pepper tops off carefully.
Remove all seeds and membranes completely.
Brush peppers with olive oil lightly.
Place peppers in baking dish upright.
Mix shredded chicken with cream cheese.
Add buffalo sauce and garlic powder.
Season mixture with salt and pepper.
Stir in half the cheddar cheese.
Add chopped green onions to mixture.
Stuff each pepper with chicken mixture.
Top with remaining cheddar cheese generously.
Cover dish with aluminum foil tightly.
Bake for 35-40 minutes until tender.
Remove foil during last 10 minutes.
Let peppers cool for 5 minutes.
Serve hot with additional buffalo sauce.