Preheat the oven to 375 degrees. Cut the tops off each bell pepper and set them aside. Use a small knife to carve simple jack-o'-lantern faces into the sides of the peppers. Remove the seeds and membranes from inside.

Place a large skillet over medium heat. Add the ground turkey, diced onion, and minced garlic. Cook until the turkey is browned and the onion softens, breaking up the meat as it cooks.

Stir in the cooked white rice, tomato sauce, salt, and black pepper. Cook for 2 minutes until everything is heated through. Remove the skillet from the heat and mix in half of the shredded cheddar cheese.

Stand the carved peppers upright in a baking dish. Spoon the turkey mixture evenly into each pepper. Place the reserved tops back on if desired.

Bake for 25 minutes. Remove the dish from the oven, sprinkle the remaining cheese over the tops of the peppers, and return to the oven for 5 more minutes until the cheese melts.