Prepare the Pasta: Bring a generous pot of salted water to a boil. Add the tri-color rotini and cook until just tender, following the package directions. Once done, drain and rinse with cold water to halt the cooking and cool the pasta.

Prepare the Dressing: In a small mixing bowl, whisk together mayonnaise, sour cream, Parmesan cheese, dried basil, dried oregano, garlic powder, salt, and pepper until smooth and well combined.

Combine Ingredients: In a large mixing bowl, combine the cooked and cooled pasta, cherry tomatoes, and green onions. Pour the creamy dressing over the pasta and gently toss to coat all the ingredients evenly.

Let It Rest: Cover the pasta salad and refrigerate for a minimum of 1 hour to let the flavors combine. Just before serving, give it a quick stir and taste, adjusting the seasoning as needed.