Preheat your oven to 400°F. In a large mixing bowl, combine the ground beef, breadcrumbs, grated Parmesan cheese, and the egg. Add Worcestershire sauce, garlic powder, onion powder, salt, and black pepper. Mix until well combined and shape into meatballs about 1.5 inches in diameter.

In a large oven-safe skillet, heat olive oil over medium heat. Add the meatballs and cook for about 5 minutes, turning occasionally until browned on all sides. Transfer the skillet to the oven and bake for 15 minutes or until cooked through.

While the meatballs are baking, boil a large pot of salted water. Add cubed russet potatoes and cook until tender, about 15-20 minutes. Drain and return to the pot. Add milk, unsalted butter, minced garlic, and chopped parsley. Mash until smooth and creamy, seasoning with salt and pepper to taste.

In a saucepan, combine beef broth, cornstarch mixed with water, soy sauce, Dijon mustard, and garlic powder. Bring to a simmer over medium heat, stirring until thickened, about 5 minutes.

To serve, place a scoop of garlic mashed potatoes on each plate, top with meatballs, and drizzle with gravy.