Preheat your oven to 400°F (200°C) and prepare your workstation with a mixing bowl and baking sheet.

In a large mixing bowl, combine the ground beef, breadcrumbs, milk, onion, garlic, egg, Worcestershire sauce, salt, pepper, parsley, onion powder, and garlic powder. Mix until well combined.

Shape the mixture into 1.5-inch meatballs and place them on a baking sheet.

Bake the meatballs for 20 minutes or until fully cooked and browned.

Peel and chop potatoes, then boil in salted water for 15-20 minutes until tender. Drain and return to pot.

Mash the potatoes with garlic, butter, milk, and parsley until creamy. Season to taste.

Prepare the gravy by cooking flour in a frying pan, then whisking in the beef broth, soy sauce, and Dijon mustard. Simmer until thickened.

Transfer baked meatballs to the gravy and coat well.

Serve meatballs over mashed potatoes, garnished with parsley.