Preheat your oven to 375°F (190°C).
In a large bowl, combine ground beef, breadcrumbs, Parmesan cheese, egg, garlic powder, onion powder, salt, and pepper.
Mix until well combined, then shape into meatballs.
In a skillet over medium heat, brown the meatballs on all sides.
Spread half of the marinara sauce in a baking dish.
Place the browned meatballs on top of the sauce.
Pour the remaining marinara sauce over the meatballs.
Sprinkle shredded mozzarella cheese evenly over the top.
Cover with foil and bake for 20 minutes.
Remove the foil and bake for an additional 10 minutes until cheese is golden.