Preheat your oven to 350°F (175°C).
In a large skillet, heat olive oil over medium heat. Add the sliced onions and sauté until caramelized.
Add the ground beef to the skillet, breaking it apart with a spatula, and cook until browned.
Stir in Worcestershire sauce, garlic powder, salt, and pepper. Mix well.
In a large mixing bowl, combine the cooked rice with the beef and onion mixture, then stir in the beef broth.
Transfer the mixture into a baking dish and top with shredded Swiss cheese.
Cover the baking dish with foil and bake for 25 minutes, then remove the foil and bake for an additional 15 minutes.
Remove from the oven and let it cool for 5-10 minutes before serving.