Preheat the oven to 375°F (190°C).
Cut the tops off the bell peppers and remove the seeds.
In a large bowl, mix shredded chicken with buffalo sauce, cream cheese, ranch dressing, and garlic powder.
Season the mixture with salt and pepper to taste.
Stuff each bell pepper with the buffalo chicken mixture.
Place the stuffed peppers upright in a baking dish.
Sprinkle shredded cheddar cheese on top of each pepper.
Cover the dish with aluminum foil and bake for 20 minutes.
Remove the foil and bake for an additional 5 minutes, until the cheese is bubbly.
Garnish with chopped green onions before serving.