
Bring a large pot of well-salted water to a boil. Cook the pasta until al dente according to the package directions, then reserve 1 cup of the pasta cooking water before draining.


While the pasta cooks, make the pesto. In a food processor, blend the arugula, feta, cashews, Parmesan, lemon zest, lemon juice, olive oil, and ice cubes until mostly smooth and creamy, scraping down the sides as needed.



Transfer the drained pasta to a large bowl or back to the warm pot. Add the pesto and toss well, adding the reserved pasta water a little at a time until the sauce coats the pasta smoothly.

Taste and adjust with more lemon juice or a small pinch of salt if needed. Serve warm, topped with extra arugula and lemon zest if desired.