Preheat oven to 375°F (190°C) and slice the tops off the bell peppers, removing the seeds and membranes.

In a skillet over medium heat, brown the ground beef along with the chopped onion until the meat is fully cooked and onions are translucent.

Stir in the minced garlic and cook for 1 minute until fragrant.

Mix the cooked rice and half of the tomato sauce (1/2 cup) into the beef mixture. Let it simmer for 3 minutes.

Arrange the hollowed-out bell peppers in a baking dish. Spoon the beef and rice mixture into each pepper cavity.

Pour the remaining 1/2 cup of tomato sauce over the filled peppers and bake for 30 minutes.

Remove from the oven, sprinkle the shredded cheese evenly over the tops, and return to the oven for 5 minutes until the cheese is melted.

Garnish with chopped fresh parsley before serving.