Preheat the oven to 350°F.
Add oil to the skillet and heat it over medium heat. Saute the onion and garlic until fragrant.
Add the ground turkey, breaking up any clumps with a spatula as it cooks. Season with salt and pepper.
Fill a saucepan about 1/4 full with water and bring it to a boil.
Cut off the tops of the bell peppers and remove the seeds and core.
Boil the bell peppers for about 5 minutes, then drain and set them aside.
Once the ground turkey is no longer pink, reduce the heat and stir in the cooked rice. Mix until well combined.
Pour in the tomato sauce and season again with salt and pepper. Bring the mixture to a gentle simmer.
Arrange the bell peppers upright in a glass baking dish. Fill each one with the turkey and rice mixture, then top with cheese.
Cover the baking dish with foil and bake for 10 minutes.
Remove the foil and bake for an additional 15 minutes, until the cheese is melted and bubbly.
Garnish the stuffed bell peppers with chopped parsley. Serve warm and enjoy!