Preheat your oven to 375°F (190°C).

Halve the Italian sub rolls lengthwise, ensuring not to cut all the way through to create a pocket.

In a small bowl, melt the unsalted butter and stir in garlic powder, onion powder, dried oregano, dried basil, red pepper flakes, salt, and black pepper until well combined.

Brush the cut sides of the rolls with the seasoned butter mixture evenly.

Layer the fillings starting with salami, followed by ham, pepperoni, mozzarella, provolone, and grated Parmesan cheese on the bottom half of each roll.

Spread roasted red pepper slices over the cheese, then add black olives and banana peppers, and garnish with fresh basil leaves.

Place the assembled sandwiches in the oven and bake for 10-12 minutes, until the cheese is melted and bubbly, and the bread is crispy and golden.

Remove the sandwiches from the oven, let them cool for about 1 minute, slice, and serve warm.