Preheat your oven to 375°F (190°C).
Cut the tops off the bell peppers and remove the seeds and membranes. Set aside.
In a skillet over medium heat, mix the shredded chicken with buffalo sauce, garlic powder, salt, and pepper. Stir until evenly coated and heated through.
In a mixing bowl, combine the chicken mixture with softened cream cheese, half of the shredded cheddar cheese, and chopped green onions. Mix until well combined.
Stuff each bell pepper with the buffalo chicken mixture, packing it down slightly. Place stuffed peppers upright in a baking dish.
Top each stuffed pepper with the remaining cheddar cheese.
Cover the baking dish with aluminum foil and bake for 20 minutes.
Remove the foil and bake for an additional 10 minutes, or until the cheese is bubbly and slightly browned.
Let the peppers cool for a few minutes before serving. Enjoy your Buffalo Chicken Stuffed Peppers!