Preheat your oven to 350 degrees Fahrenheit.
Put the peppers in a large microwave-safe bowl. Spray liberally with cooking spray. Cover the bowl with a microwave-safe plate and microwave for 7 minutes (see note).
4 bell peppers
While the peppers are cooking in the microwave, heat a large skillet over medium heat. Add the olive oil and then add the onions. Cook the onions for approximately 7 minutes or until very soft.
1 tablespoon olive oil, 1/2 large onion
Add the garlic and sauté for another minute.
2 cloves garlic
Add the ground turkey, breaking it up as you cook it. Add in the Italian seasoning, salt, pepper, and cumin.
1 pound ground turkey, 2 teaspoons Italian seasoning, 1/2 teaspoon salt, 1/4 teaspoon pepper, 1 teaspoon cumin
Once the turkey is completely cooked through, stir in the spaghetti sauce, 1 cup of mozzarella cheese, and cooked rice.
1 cup spaghetti sauce, 2 cups mozzarella cheese, 1 1/2 cups cooked rice
Put the peppers on a parchment-lined baking tray, discarding any liquid that might have accumulated during microwaving. Divide the filling mixture among the eight pepper halves and then top with the remaining cheese.
Bake the peppers for 15 to 20 minutes until the cheese completely melts and begins to bubble. Top with fresh parsley if desired.