Cover the cashews with boiling water and soak for 15 minutes. Drain and blend with the water, mayonnaise, lime juice, nutritional yeast, garlic and salt until silky smooth.
Cook the pasta in a large pot of salted boiling water until al dente. Reserve 1/2 cup of the pasta water, then drain.
Heat the olive oil in a large skillet over medium high heat. Spread the corn in an even layer and cook undisturbed for 3 to 4 minutes until charred in spots, then stir and cook for another 3 to 4 minutes.
Add the jalapeno, garlic, chili powder and smoked paprika and cook for 1 minute until fragrant.
Reduce the heat to low. Add the pasta, lime crema and a splash of the pasta water and toss until everything is creamy and coated.
Top with feta crumbles, cilantro, green onions and a sprinkle of chili powder. Serve with lime wedges for squeezing.