Preheat your oven to 375°F (190°C).

In a large skillet, heat the marinara sauce over medium heat. Add the frozen meatballs to the skillet and cook, stirring occasionally, until the meatballs are heated through (about 10-12 minutes).

Split the mini sub rolls open and place them on a baking sheet.

Spoon the meatballs and marinara sauce into each sub roll, distributing them evenly.

Sprinkle a generous amount of shredded mozzarella cheese over the top of each meatball sub.

Sprinkle a bit of Italian seasoning over each sub for extra flavor.

Place the baking sheet in the preheated oven and bake for 5-7 minutes, or until the cheese is melted and bubbly.

Remove from the oven and let the subs cool for a few minutes before serving.

Serve hot and enjoy!