01 - Preheat oven to 375°F. Lightly grease a baking dish.
02 - Slice the tops off bell peppers and remove seeds and membranes. Place peppers upright in the baking dish.
03 - In a large skillet, heat olive oil over medium heat. Sauté onion for 2–3 minutes until softened. Add garlic and cook for another 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, oregano, 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 - Let the mixture cool slightly, then gently fold in crumbled feta cheese.
07 - Spoon the chicken mixture into each bell pepper, packing gently to fill evenly.
08 - Pour chicken broth into the bottom of the baking dish to keep peppers moist during baking. Cover tightly with aluminum foil.
09 - Bake covered for 30 minutes. Remove foil and bake an additional 10 minutes until peppers are tender and tops are slightly golden.
10 - Garnish with extra fresh herbs and crumbled feta before serving, if desired.