Southwestern Stuffed Pepper Casserole

lean ground beef

onion, chopped

garlic cloves, finely minced

small green peppers, or about 1 C chopped pepper

salt

cooked brown rice

jar reduced-sodium spaghetti sauce or homemade sauce

frozen corn, thawed

black beans

tomatoes, chopped

shredded cheese, divided (I used a combination of mozzarella and sharp cheddar.)