Slice the tops off the bell peppers and remove the seeds and membranes. Set them aside.
In a large skillet, heat the olive oil over medium heat. Add the chopped onion and minced garlic, sautéing until the onion is translucent, about 3 minutes.
Increase the heat to medium-high and add the ground chicken to the skillet. Cook until browned, breaking it apart with a spoon, about 5-7 minutes.
Stir in the cauliflower rice, hot sauce, smoked paprika, onion powder, salt, and pepper. Cook for an additional 3-4 minutes until everything is heated through and well combined.
Spoon the buffalo chicken mixture into each bell pepper until they are packed tightly.
Place the stuffed peppers upright in a baking dish and cover with foil. Bake for 25-30 minutes, then remove the foil and bake for an additional 10-15 minutes, or until the peppers are tender.
Remove from the oven and let cool slightly. Garnish with sliced green onions and fresh cilantro before serving.