01 - Cook the pasta in a large pot of boiling salted water according to the package directions until al dente. Drain, rinse with cold water, and set aside.
02 - Preheat a grill or grill pan over high heat. Grill the ears of corn, rotating until all sides are lightly charred, about 8 to 10 minutes. Allow corn to cool, then cut kernels from the cobs. If using frozen corn, sauté in a dry skillet over high heat until kernels are slightly charred.
03 - In a large mixing bowl, whisk together mayonnaise, sour cream, fresh lime juice, chili powder, smoked paprika, ground cumin, salt, and black pepper until the mixture is smooth.
04 - Add the cooked pasta, charred corn kernels, diced red bell pepper, sliced green onions, chopped cilantro, crumbled Cotija cheese, and diced jalapeño (if using) to the bowl. Toss thoroughly to coat all ingredients evenly with the dressing.
05 - Taste and adjust seasoning as desired. Cover and refrigerate for at least 30 minutes before serving to allow flavors to develop.