Preheat the oven to 350°F (175°C). Lightly grease a 9x13-inch baking dish or line it with foil for easier cleanup.

Without separating the rolls, slice the entire slab of rolls in half horizontally. Place the bottom halves in the prepared baking dish.

Spread the mayonnaise and Dijon mustard evenly over the bottom layer of rolls.

Layer half of the provolone over the rolls, then add the ham, salami, pepperoni, and banana peppers or pepperoncini. Top with the remaining provolone and place the top halves of the rolls on top.

In a small bowl, stir together the melted butter, Italian seasoning, garlic powder, and Parmesan cheese. Brush the mixture evenly over the tops of the sliders.

Cover the baking dish with foil and bake for 15 minutes. Remove the foil and bake for 5 to 7 minutes more, or until the tops are golden and the cheese is melted.

If using, sprinkle with chopped parsley. Let the sliders rest for 2 to 3 minutes, then separate and serve warm.