Cook the pasta: Bring a large pot of salted water to boil. Add pasta and cook according to package directions until al dente (about 10-12 minutes). Drain thoroughly and rinse with cold water to stop cooking and cool the pasta completely.

Prepare vegetables: While pasta cooks, slice green onions, finely chop parsley, and dice jalapeño, if using.

Combine dry ingredients: In a large mixing bowl, combine the cooled pasta, drained corn, crumbled cotija cheese, sliced green onions, chopped parsley, and diced jalapeño. Toss gently to distribute evenly.

Make the dressing: In a small bowl, whisk together mayonnaise, fresh lime juice, black pepper, salt, and chili powder until smooth and well combined.

Assemble salad: Pour the dressing over the pasta mixture and toss thoroughly until all ingredients are evenly coated.

Chill and serve: Cover and refrigerate for at least 1 hour to allow flavors to meld. Stir gently before serving. Serve chilled as a side dish.