1. In a large bowl, combine the ground beef, breadcrumbs, egg, Parmesan, garlic, onion, parsley, salt, pepper, onion powder, and garlic powder. Mix until just combined.

2. Roll the mixture into evenly sized meatballs.

3. Heat some olive oil in a large skillet and brown the meatballs on all sides, then set them aside.

4. In the same skillet, melt the butter and sauté the mushrooms until they’re browned and softened.

5. Sprinkle in the flour and cook for a minute or two, then slowly pour in the beef broth while stirring continuously to prevent lumps.

6. Add the Worcestershire sauce and thyme, and let the gravy simmer and thicken.

7. Stir in the heavy cream and season with salt and pepper to taste.

8. While the gravy is simmering, boil the diced potatoes in salted water until fork-tender.

9. Drain them, then mash them with butter and milk until they’re creamy and smooth.

10. Season with salt and pepper to your liking.

11. Return the meatballs to the skillet, nestling them in the rich mushroom gravy.

12. Let everything simmer for about 10 minutes.