Preheat oven to 375 degrees F. Lightly grease a 9x13 inch baking dish. Cook rice according to package directions if not already prepared.
Wash bell peppers and cut off tops about half an inch from stem. Remove all seeds and membranes. Arrange peppers upright in prepared baking dish. Drizzle with olive oil and sprinkle with pinch of salt. Bake for 10 minutes to start softening.
While peppers bake, heat a large skillet over medium-high heat. Add ground beef and diced onion, breaking up meat as it cooks. Cook 6 to 8 minutes until beef is browned and onions are translucent. Drain excess fat.
Add minced garlic to beef mixture and cook 1 minute. Stir in cooked rice, drained diced tomatoes, half the tomato sauce, corn, Worcestershire sauce, Italian seasoning, paprika, salt, and black pepper. Cook 3 to 4 minutes, stirring occasionally.
Remove from heat and fold in 1 cup mozzarella cheese. Remove partially baked peppers from oven. Spoon beef and rice filling into each pepper, packing gently and filling to the top.
Pour remaining tomato sauce evenly over stuffed peppers. Cover baking dish tightly with aluminum foil. Bake covered for 30 minutes until peppers are tender when pierced with a fork.
Remove foil and sprinkle remaining 1/2 cup mozzarella cheese over tops of peppers. Bake uncovered 10 to 15 minutes until cheese is melted, bubbly, and starting to brown. Let rest 5 minutes before serving. Garnish with fresh parsley.