01 - Preheat oven to 375°F. Bring large pot of salted water to a boil, blanch bell peppers for 3 minutes, drain, and set upside down to dry.
02 - Heat olive oil in skillet over medium heat. Sauté onion for 3–4 minutes until softened, then add garlic and cook for 1 minute.
03 - Add ground beef, cook breaking up until browned and fully cooked. Drain excess fat if needed.
04 - Stir in diced tomatoes, cooked rice, half the cheese, parsley, oregano, salt, black pepper, paprika, and red pepper flakes. Cook 2–3 minutes until heated through.
05 - Place blanched peppers upright in baking dish. Fill each evenly with beef mixture.
06 - Sprinkle remaining shredded cheese over stuffed peppers.
07 - Pour ¼ cup water into bottom of baking dish and cover loosely with foil.
08 - Bake covered for 30 minutes. Remove foil and bake additional 10–15 minutes until cheese is golden and peppers are tender.
09 - Allow to cool slightly before serving.