Make the Italian dressing first. Combine olive oil, red wine vinegar, Dijon mustard, garlic powder, Italian seasoning, salt, pepper, and Parmesan in a bowl. Whisk until combined.

Cook the rotini according to package directions (7-10 minutes), then drain and rinse with cool water.

While the pasta cooks, cut the pepperoni and chop the mozzarella, bell pepper, and red onion.

Once the pasta is cooled, transfer to a large bowl. Add pepperoni, mozzarella, bell pepper, red onion, banana peppers, and black olives. Toss to combine.

Shake the dressing again and drizzle it over the pasta salad. Toss to coat.