In a large mixing bowl, combine ground beef, bread crumbs, Parmesan cheese, minced garlic, egg, salt, black pepper, and Italian seasoning. Mix until well combined.

Form Meatballs

Shape the mixture into meatballs, about 1.5 inches in diameter. Place them on a baking sheet lined with parchment paper.

Bake Meatballs

Preheat the oven to 400°F (200°C). Bake the meatballs for 20-25 minutes or until cooked through and browned.

Marinara Sauce Preparation

Sauté Vegetables

In a large saucepan, heat olive oil over medium heat. Add chopped onion and sauté until translucent, about 5 minutes. Add minced garlic and sauté for an additional minute.

Combine Ingredients

Add crushed tomatoes, dried basil, sugar, salt, and black pepper to the saucepan. Stir well to combine.

Simmer Sauce

Bring the sauce to a simmer. Reduce heat to low and let it cook for about 15-20 minutes, stirring occasionally.

Assembly

Combine Meatballs and Sauce

Once the meatballs are cooked, add them to the marinara sauce. Stir gently to coat the meatballs with the sauce.

Prepare Sub Rolls

Slice the sub rolls lengthwise without cutting all the way through. Place them on a baking sheet.

Assemble Subs

Spoon the meatball and marinara sauce mixture into each sub roll. Top with shredded mozzarella cheese.

Melt Cheese

Place the assembled subs in the oven under the broiler for 2-3 minutes until the cheese is melted and bubbly.

Garnish and Serve

If desired, garnish with fresh basil. Serve hot and enjoy your hearty meatball sub!