Preheat your oven to 350°F (175°C).
In a large skillet, heat the olive oil over medium heat. Add the chopped onion and cook until softened, about 5 minutes.
Add the ground beef to the skillet and cook until browned, breaking it apart with a wooden spoon. Season with garlic powder, onion powder, salt, and pepper. Drain excess fat if necessary.
Once the beef is cooked, stir in the uncooked rice, cream of mushroom soup, beef broth, and diced tomatoes. Mix well until all ingredients are combined.
Transfer the mixture to a 9x13-inch baking dish, spreading it evenly.
Cover the dish with aluminum foil and bake in the preheated oven for 25 minutes.
After 25 minutes, remove the foil and sprinkle the shredded cheddar cheese on top. Return to the oven and bake for an additional 5 minutes, or until the cheese is melted and bubbly.
Allow the casserole to cool for a few minutes before serving. Enjoy!