Preheat the oven: Set to 425°F (220°C).
Melt the butter: Place the stick of butter in a 9x9-inch baking dish and melt in the oven for 4-5 minutes, watching to avoid burning.
Mix in the rice: Remove the dish and stir in the uncooked rice, coating it thoroughly in the butter.
Add liquids and seasoning: Pour in the beef broth and French onion soup. Add garlic powder, salt, and pepper if desired, and stir gently.
Cover and bake: Seal tightly with foil and bake for 30 minutes.
Fluff and serve: Remove foil and check if rice is tender and liquid absorbed. If needed, bake uncovered for 5 more minutes. Fluff with a fork and garnish with parsley.