Bring a large pot of salted water to a rolling boil. Add the tri-color rotini pasta and cook according to package directions until al dente, about 8-10 minutes. Drain and rinse under cold water until cool.

In a mixing bowl, combine the cooled rotini pasta with cherry tomatoes, sliced pepperoni, red onion, green bell pepper, mozzarella, grated parmesan, and olives. Gently toss to mix.

In a separate bowl, whisk together olive oil and red wine vinegar until emulsified. Add Italian seasoning, garlic powder, salt, pepper, and red pepper flakes, whisking to combine.

Pour the vinaigrette over the pasta mixture and toss to coat. Cover and refrigerate for at least 1 hour to chill.

Before serving, let the salad sit at room temperature for 20-30 minutes, then toss again to redistribute the ingredients.