Preheat the oven to 350°F (175°C). Lightly grease or line a 9×13-inch baking dish with parchment paper for easy cleanup.

Slice the rolls: Keeping the rolls attached, slice the entire slab in half horizontally. Place the bottom half in the prepared baking dish.

Layer the fillings: Add half the provolone cheese. Top with an even layer of ham, followed by the salami, then the pepperoni. Sprinkle the sliced pepperoncini evenly over the top. Add the remaining provolone slices. Place the top half of the rolls back on.

Add half the provolone cheese.

Top with an even layer of ham, followed by the salami, then the pepperoni.

Sprinkle the sliced pepperoncini evenly over the top.

Add the remaining provolone slices.

Place the top half of the rolls back on.

Make the garlic butter topping:In a small bowl, combine melted butter, Parmesan, italian seasoning, garlic, and red pepper flakes (if using). Stir until combined.

Brush the rolls:Use a pastry brush or spoon to coat the tops of the rolls with the garlic-Parmesan butter mixture, letting it drip into the sides.

Bake:Cover the dish with foil and bake for 15 minutes. Remove the foil and bake uncovered for an additional 5–8 minutes, or until the tops are golden and the cheese is melted.

Serve:Let cool for a few minutes, then slice and serve warm!