Cook the pasta: Bring a large pot of salted water to boil. Add rotini 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 the corn: If using fresh corn, brush ears with olive oil and grill over medium-high heat, turning every few minutes until lightly charred all over, 10-15 minutes. Let cool, then cut kernels off the cob. If using canned corn, drain and rinse well.

Make the dressing: In a small bowl, whisk together mayonnaise, Mexican crema, lime juice, chili powder, smoked paprika, and garlic powder until smooth and well combined. Season with salt and pepper to taste.

Combine salad: In a large mixing bowl, combine cooled pasta, corn kernels, crumbled cotija cheese, sliced green onions, chopped cilantro, and diced jalapeño if using. Toss gently to distribute evenly.

Add dressing: Pour the dressing over the pasta mixture and toss thoroughly until all ingredients are evenly coated with the creamy lime-chili sauce.

Chill and serve: Cover and refrigerate for at least 1 hour to allow flavors to meld. Stir gently before serving. Garnish with extra cotija cheese and fresh cilantro if desired. Serve chilled.