Preheat oven to 375°F and lightly spray a 9x13 baking dish with nonstick spray.
Keeping the rolls connected, slice the package horizontally in half.
Remove the top row of connected buns and set aside.
Place the bottom row of buns in the prepared baking dish.
Sprinkle 1 cup of shredded mozzarella evenly over the bottom buns.
Spread pizza sauce over the mozzarella layer.
Layer 20 slices of pepperoni evenly over the sauce.
Sprinkle the remaining shredded mozzarella over the pepperoni.
Place the top row of buns evenly over the cheese.
Brush melted butter over the top buns using a pastry brush.
Sprinkle grated Parmesan and dried Italian seasoning on top.
Cover the dish with aluminum foil and bake for 25 minutes.
Remove from oven, slice into individual sliders, and serve warm.