Cook the pasta in a large pot of salted water until al dente. Drain, toss with a drizzle of olive oil, and let cool to room temperature (or chill in the fridge).
Meanwhile, melt the butter in a large skillet over medium-high heat. Add the corn and cook, stirring occasionally, for about 10 minutes, until some kernels are charred. Transfer to a plate to cool.
In a small bowl, whisk together the mayonnaise, sour cream, lime juice, lime zest, chili powder, smoked paprika, garlic powder, salt, and pepper until smooth.
Add the cooled pasta, charred corn, cilantro, green onions, and most of the cotija to a large bowl. Pour the dressing over the top and toss until well coated.
Garnish with the remaining cotija, extra cilantro, and a sprinkle of chili powder. Serve immediately or refrigerate until ready.