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 onion for 2 to 3 minutes until softened. Add garlic and cook for 30 seconds until fragrant.
04 - Add ground chicken to the skillet. Cook, breaking it apart with a spoon, until no longer pink, about 5 to 7 minutes.
05 - Stir in diced tomato, chopped spinach, parsley, dill, oregano, cumin, paprika, salt, and pepper. Cook for 2 to 3 minutes. Mix in cooked rice or quinoa if using, then remove from heat.
06 - Let the mixture cool slightly, then gently fold in the 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 and bake for 30 minutes.
09 - Remove the foil and continue baking for an additional 10 minutes until peppers are tender and tops are lightly golden.
10 - Garnish with extra fresh herbs and crumbled feta before serving if desired.