Prep the peppers: Heat the oven to 375°F (190°C).
Slice the tops off the bell peppers and remove seeds and membranes. If they don’t stand upright, shave a thin slice from the bottoms to steady them. Place in a baking dish, cut side up.
Soften the peppers (optional but helpful): Add a splash of water to the dish and cover tightly with foil.
Bake for 10 minutes to jump-start tenderizing. Set aside.
Sauté the aromatics: Heat olive oil in a large skillet over medium. Add onion and celery with a pinch of salt.
Cook 3–4 minutes until softened. Stir in garlic and cook 30 seconds until fragrant.
Brown the chicken: Add ground chicken, breaking it up with a spoon. Season with smoked paprika, cayenne (if using), salt, and pepper.
Cook until the chicken is no longer pink, 5–7 minutes.
Make it Buffalo: Lower the heat. Stir in Buffalo sauce and butter. Simmer 1–2 minutes until glossy.
Fold in Greek yogurt or cream cheese to add a little creaminess and help the filling set.
Add the base: Stir in cooked rice or cauliflower rice and half the green onions. Taste and adjust salt, pepper, and heat. The filling should be saucy but not runny.
Stuff the peppers: Spoon the Buffalo chicken mixture into each pepper, packing it in gently.
Top with mozzarella or Jack.
Bake: Return the dish to the oven and bake 15–20 minutes, until the peppers are tender and the cheese is melted and lightly browned.
Finish with tang: Sprinkle with blue cheese crumbles and remaining green onions. Let rest 5 minutes so the filling sets slightly.
Serve: Drizzle with a little extra Buffalo sauce or ranch. Plate with a crisp side salad, cucumber sticks, or roasted potatoes.