Cut the tops off the bell peppers and remove the seeds and membranes. Arrange them upright in a baking dish.
In a mixing bowl, combine the shredded cooked chicken, buffalo sauce, cream cheese, half of the cheddar cheese, diced celery, garlic powder, onion powder, salt, and pepper. Mix until well combined.
Spoon the buffalo chicken mixture into each of the prepared bell peppers, pressing down slightly to pack filling.
Top each stuffed pepper with the remaining cheddar cheese and blue cheese crumbles (if using).
Cover the baking dish with aluminum foil and bake for 25 minutes.
Remove the foil and bake for an additional 10-15 minutes, or until the peppers are tender and the cheese is bubbly and golden.
Remove from oven and let cool slightly before serving. Garnish with fresh parsley or green onions for added flavor and color.
Notes
Adjust buffalo sauce to taste for desired spiciness.