Cut the tops off the bell peppers and remove the seeds and membranes. Lightly drizzle olive oil over the outside of the peppers and place them upright in a baking dish.
In a mixing bowl, combine the shredded chicken, buffalo sauce, cream cheese, half of the cheddar cheese, and blue cheese crumbles if using. Stir until everything is well incorporated and creamy.
Season the mixture with salt and pepper to taste.
Carefully stuff each bell pepper with the buffalo chicken mixture, pressing down gently to pack it in.
Sprinkle the remaining cheddar cheese on top of the stuffed peppers.
Bake in the preheated oven for 25-30 minutes, or until the peppers are tender and the cheese is bubbly and golden.
Remove from the oven and let cool for a few minutes. Garnish with sliced green onions before serving.
Notes
Serve with extra buffalo sauce and a side of ranch or blue cheese dressing for dipping.