Preheat the Oven:
Preheat your oven to 350°F (175°C). Prepare a 9×13 inch baking dish (or two smaller dishes) by spraying them generously with cooking spray.
Cook the Beef and Onion:
In a large saucepan over medium heat, brown the lean ground beef and soften the chopped onion until the meat is no longer pink. Drain off any excess fat if needed. Once cooked, transfer the mixture to a large mixing bowl.
Combine the Ingredients:
Add the tomato sauce, chopped cabbage, uncooked rice, salt, pepper, and garlic powder to the bowl with the beef mixture. Stir all the ingredients together until they are well combined.
Assemble the Casserole:
Pour the mixture into the prepared baking dish (or dishes). Carefully pour the beef broth over the top, making sure not to stir.
Bake the Casserole:
Cover the dish with aluminum foil and bake in the preheated oven for 1 hour.
Finish Baking:
