Place frozen rolls on a lightly oiled or buttered baking sheet, cover loosely with a dish towel or plastic wrap that has been sprayed with cooking spray.
Set in a warm area of your kitchen for 3-5 hours until the rolls have thawed and risen to double in size.
Preheat the oven to 350
Cut your string cheeses into 3 equal parts.
Gently flatten the risen dough balls into a circle.
Place 4 slices of pepperoni in the center of the dough circle and place a piece of string cheese on top.
Fold in two sides and press them together in the center.
Fold in the ends and press to seal the dough shut around the pepperoni and cheese.
Place the pepperoni roll seam side down on the baking sheet.
Repeat until all the dough has been made into pepperoni rolls
Bake for 10 minutes.
Remove from the oven and brush the tops with melted butter or olive oil and sprinkle with parmesan cheese.
Place the pepperoni rolls back in the oven for another 5-8 minutes or until the tops are golden brown.