01 - Preheat the oven to 350°F.
02 - Slice off the tops of the bell peppers and remove seeds and membranes. Set aside.
03 - Heat olive oil in a large skillet over medium heat. Add chopped onion and sauté until softened, about 3 minutes.
04 - Add minced garlic and cook for 1 minute. Incorporate ground beef and cook until browned, breaking it apart with a spoon.
05 - Stir in diced zucchini and tomato, cooking for 3 minutes until slightly softened.
06 - Mix in rinsed rice, tomato paste, parsley, mint, oregano, cumin, cinnamon, salt, and pepper. Cook for 2 to 3 minutes, stirring thoroughly.
07 - Remove the filling from heat. Stuff each bell pepper with the mixture, pressing gently. Place peppers upright in a baking dish.
08 - Pour broth into the base of the baking dish. Sprinkle each stuffed pepper with crumbled feta and pine nuts, if using.
09 - Cover the baking dish loosely with foil and bake for 35 minutes.
10 - Remove foil and bake uncovered for an additional 10 minutes until peppers are tender and feta is lightly golden.
11 - Allow the stuffed peppers to rest for 5 minutes before serving.