1. Preheat the oven to 375°F and lightly grease a 9×13-inch baking dish.

2. In a large skillet over medium heat, cook the ground beef until browned, then add the chopped onion and cook until softened. Drain any excess grease.

3. Peel and slice the potatoes and carrots into even pieces, then spread them in the prepared baking dish.

4. Spoon the cooked beef and onion mixture evenly over the vegetables.

5. In a medium bowl, whisk together the cream of mushroom soup, beef broth, Worcestershire sauce, garlic powder, salt, black pepper, and melted butter until smooth.

6. Pour the gravy mixture evenly over the beef and vegetables.

7. Cover the dish tightly with foil and bake for 50 minutes.

8. Remove the foil and bake for another 20 to 25 minutes, until the potatoes and carrots are tender and the top is bubbling.

9. Let the casserole rest for 10 minutes, then sprinkle with fresh parsley and serve warm.