01 - Preheat oven to 375°F. Slice tops off bell peppers, remove seeds and membranes, and brush lightly with olive oil.
02 - Heat 1 tablespoon olive oil in a large skillet over medium heat. Sauté onion for 2–3 minutes until soft, add garlic, and cook for 1 minute.
03 - Stir chopped spinach into the skillet and cook for 2 minutes until wilted. Remove from heat.
04 - In a large bowl, combine cooked chicken, spinach mixture, ricotta, 1/2 cup mozzarella, Parmesan, Italian herbs, salt, and pepper.
05 - Pack each bell pepper evenly with the chicken Florentine mixture and arrange upright in a baking dish.
06 - Spoon marinara sauce over peppers. Pour 1/4 cup water into the dish bottom, cover with foil, and bake for 25 minutes.
07 - Remove foil, sprinkle with remaining mozzarella, and bake for 10 minutes until cheese is golden and peppers are tender.