Set your oven to 350°F and let it preheat while you prepare the sliders. Arrange a 12-pack of Hawaiian sweet rolls in a baking dish or on a rimmed baking sheet. Using a small knife, carefully cut a circular hole in the center of each slider roll, going about three-quarters of the way down. Gently press the cut-out portion into the roll to create a well. This space will hold the meatballs and toppings, ensuring nothing spills out.

Melt 3 tablespoons of butter in a small bowl. Use a pastry brush to generously coat the tops, sides, and inside wells of the rolls with the melted butter. This step adds flavor and helps the rolls turn golden and crisp. Sprinkle 1 teaspoon of garlic powder evenly over the buttered rolls for a savory kick.

Sprinkle a small amount of shredded mozzarella cheese into each well to create a cheesy base for the meatballs. Place one fully cooked frozen meatball into each roll, gently pressing it down so it sits snugly in the well.

Spoon about 1 tablespoon of marinara sauce over each meatball, spreading it slightly to cover the top. Evenly sprinkle the remaining mozzarella cheese over the meatballs and rolls, making sure each slider gets a generous layer of gooey, melty goodness.

Finish with a sprinkle of grated Parmesan cheese and a light dusting of dried parsley flakes. These toppings add extra flavor and a pop of color, making the sliders look as good as they taste.

Transfer the baking dish to the oven and bake for 18-20 minutes, or until the cheese is fully melted and bubbly, and the tops of the rolls are lightly golden. Keep an eye on them during the last few minutes to avoid overbaking.