Split rolls and place on a foil lined cookie sheet. Sprinkle each half with shredded Mozzarella cheese and a little Italian seasoning. (Optional step: you can also brush with melted butter and add a little sprinkle of garlic powder or salt before adding the cheese). Set aside.
Heat a saucepan on the stove over medium heat. Add fresh or frozen meatballs and sauce. Heat until meatballs are heated through; about 5-10 minutes.
Meanwhile, bake rolls in the oven just until the cheese is melted and the edges of the bread are golden; 3-5 minutes.
Place one meatball on half of each roll and top with more cheese, if desired. Replace tops of the sliders the other half.