01 -
Preheat oven to 350°F (175°C) and lightly grease a 9x13 inch baking dish.
02 -
In a skillet over medium heat, brown the ground beef with chopped mushrooms and diced onion until beef is thoroughly cooked. Drain any excess fat.
03 -
In a large bowl, thoroughly combine the cooked beef mixture, uncooked white rice, cream of mushroom soup, beef broth, sour cream, garlic powder, salt, and black pepper.
04 -
Pour the entire mixture into the prepared baking dish and use a spatula to create an even layer.
05 -
Cover the baking dish with aluminum foil and bake for 50 to 60 minutes, until rice is tender and most liquid has been absorbed.
06 -
Remove foil, sprinkle shredded cheddar cheese evenly over the surface if desired, and bake uncovered for 5 minutes until cheese is melted.
07 -
Allow the casserole to rest for several minutes before portioning and serving.