01 - Preheat oven to 375°F. Lightly grease a baking dish with olive oil or cooking spray.
02 - Slice the tops off bell peppers and remove all seeds and membranes. Place peppers upright in the prepared baking dish.
03 - In a large skillet, heat olive oil over medium heat. Sauté the red onion for 2–3 minutes until softened. Add minced garlic and cook for 30 seconds until fragrant.
04 - Add ground chicken to the skillet. Cook, breaking apart with a spoon, until no longer pink, about 5–7 minutes.
05 - Stir in diced tomato, chopped spinach, parsley, dill, dried oregano, ground cumin, paprika, salt, and pepper. Cook for 2–3 minutes until spinach wilts. Fold in cooked rice or quinoa if using, then remove from heat.
06 - Allow the mixture to cool slightly, then gently fold in crumbled feta cheese.
07 - Spoon the chicken mixture into each bell pepper, packing gently to fill completely.
08 - Pour chicken broth into the bottom of the baking dish to keep peppers moist. Cover tightly with aluminum foil and bake for 30 minutes.
09 - Remove foil and bake for an additional 10 minutes until peppers are tender and tops are slightly golden. Garnish with extra herbs and feta before serving.