A loaded meatball hoagie smothered in marinara and melted mozzarella is a protein-packed, family-favorite sub. This hearty Italian-American sandwich satisfies big appetites with every bite.
Preheat oven to 400°F (200°C). Line a baking sheet with parchment and brush with 1 tbsp olive oil.
In a large bowl, combine ground beef, egg, breadcrumbs, parmesan, garlic, oregano, salt, and black pepper. Mix gently by hand until just incorporated.
Shape mixture into 12 equal meatballs. Arrange evenly on the prepared baking sheet; brush or drizzle with remaining olive oil.
Bake for 18–20 minutes until browned and just cooked through. While meatballs bake, warm marinara sauce in a skillet over low heat, stirring occasionally.
Transfer meatballs to the skillet; simmer gently in sauce for 5 minutes so flavors meld without overcooking.
Split sub rolls, toast lightly if desired, and arrange meatballs with sauce inside each roll. Top with shredded mozzarella and a sprinkle of parmesan if desired.
Broil assembled hoagies on a baking tray for 2–3 minutes, watching closely, just until cheese is melted and bubbling. Serve hot.