Preheat oven to 375°F (190°C).
In a mixing bowl, combine ground beef, breadcrumbs, milk, egg, garlic, Parmesan, Italian seasoning, salt, and pepper.
Mix until just combined without overworking.
Shape the mixture into evenly sized meatballs.
Heat olive oil in an oven-safe skillet over medium heat.
Brown meatballs on all sides for 5–6 minutes.
Pour marinara sauce over the meatballs evenly.
Sprinkle shredded mozzarella cheese on top.
Transfer skillet to the oven and bake for 20 minutes.
Remove from oven once cheese is melted and bubbly.
Garnish with fresh parsley and serve hot.