1. Preheat the oven to 375°F (190°C).
2. If using frozen meatballs, cook them according to package instructions. If making homemade meatballs, mix ground beef, breadcrumbs, Parmesan cheese, eggs, herbs, and spices, then shape into small meatballs and cook until browned.
3. Slice the Hawaiian rolls in half horizontally without separating them individually.
4. Hollow out a small portion of the bottom half of each roll to create a pocket for the meatballs.
5. Place a slice of mozzarella cheese inside each hollowed-out roll.
6. Place one cooked meatball into each pocket on top of the cheese.
7. Spoon marinara sauce over each meatball.
8. Add another layer of mozzarella cheese on top of the meatballs and sauce.
9. Place the top half of the rolls back over the sandwiches.
10. In a small bowl, mix melted butter with garlic and herbs.
11. Brush the garlic butter mixture over the tops of the rolls.
12. Place the assembled sliders in a baking dish and cover loosely with foil.
13. Bake in the preheated oven for 10-15 minutes, or until the cheese is melted and the rolls are warm.
14. Remove the foil and bake for another 5 minutes, until the tops are golden brown.
15. Remove from the oven and garnish with fresh basil or parsley.
16. Let the sliders cool for a few minutes before serving.
17. Serve with extra marinara sauce on the side for dipping.
18. Enjoy your mini meatball sliders as an appetizer, snack, or meal!