01 - Cook pasta in a large pot of salted boiling water according to package directions until al dente. Drain and rinse under cold water to stop cooking. Set aside.
02 - Grill fresh corn on a preheated grill or grill pan, turning occasionally, until lightly charred on all sides, about 8 to 10 minutes. Allow corn to cool, then carefully slice kernels off the cobs. For frozen corn, sauté in a dry skillet over high heat until slightly charred.
03 - In a large mixing bowl, whisk together mayonnaise, sour cream, lime juice, chili powder, smoked paprika, ground cumin, salt, and black pepper until well blended.
04 - Add cooked pasta, charred corn kernels, red bell pepper, green onions, cilantro, Cotija cheese, and jalapeño (if using) to the bowl with dressing. Toss thoroughly to coat evenly.
05 - Taste and adjust seasoning as needed. Cover and refrigerate for at least 30 minutes to allow flavors to develop before serving.