Layer the pepperoni slices over the top of the sauce, and sprinkle the remaining shredded cheese over top of the pepperoni.
Carefully place the top set of buns on top of the sandwich filling ingredients. Using a pastry brush, brush the melted butter over the top of the buns and sprinkle the grated parmesan cheese and Italian seasoning over the melted butter.
Cover the pan with foil and place it in the freezer.
Thaw.
Preheat the oven to 350°.
Place the covered pan in the oven to bake for 25 minutes, until the cheese is melted and the buns are toasted. If you want to have crispier buns, uncover the buns for the last five minutes.
Slice the rows to form individual sliders and serve while warm.