01 -
Heat the oven to 350°F.
02 -
Prepare a deep 9-by-13-inch baking dish with room below the rim.
03 -
Heat the tablespoon of oil in a skillet and soften the diced onion.
04 -
Add the ground beef, break it apart and cook to 160°F; drain excess fat.
05 -
Whisk the two undiluted soups into the two cups of broth.
06 -
Spread beef, onion and uncooked rice in the dish, then stir in the soup mixture until evenly distributed.
07 -
Cover tightly with foil and bake about 60 minutes.
08 -
Check rice in the center and near an edge; continue covered as needed until tender, adding a little hot broth only if the pan is drying.
09 -
Remove the cover, scatter the mozzarella and return to the oven about 10–15 minutes. Verify the casserole center reaches 165°F, then rest briefly before spooning out portions.