1. Preheat the oven to 375°F.
2. Heat oil in a large pan over medium heat.
3. Once the pan is hot, sauté onions and garlic until soft and fragrant, approximately 3 minutes.
4. Add ground beef to the pan and cook for another 5 to 6 minutes.
5. Once the beef is cooked, stir in the cooked rice, diced tomatoes, tomato paste, dried oregano, smoked paprika, salt, and pepper and cook for another 5 to 6 minutes.
6. While the beef mixture cooks and combines, cut the tops off the peppers and core them so they're empty.
7. Once the beef mixture is cooked, stuff it into the peppers, then place them in a rimmed baking dish, and then place the dish in the oven to cook for approximately 10 minutes.
8. Remove the peppers from the oven and cover them with the shredded cheese, placing them back in the oven for approximately 5 minutes.
9. Once the cheese has melted, remove the peppers from the oven, garnish them with parsley, and serve!
