Preheat oven to 375℉
In a large skillet, sauté the onion in olive oil until soft
Add the beef, and cook until no longer pink, breaking it up with a spatula as it cooks. Drain grease if needed
Season with 1 tsp salt, garlic, paprika and pepper
Stir in the diced tomatoes, rice and 1 cup beef broth, and simmer on low heat until rice is cooked -- about 5 minutes. Set aside
Slice peppers from the stem to the bottom. Remove membranes and seeds, and rinse
In a large baking dish, stir the tomato soup and remaining cup beef broth until combined
Place peppers, cut sides up in casserole dish, and season insides with remaining salt
Spoon filling into peppers, packing it tightly
Cover loosely with aluminum foil, and bake in preheated oven for 30 minutes or until peppers are tender and sauce is bubbling.
Spoon some sauce over filling, top with cheese, if using, and return to oven uncovered until cheese melts. Spoon additional sauce over peppers when serving, if desired