Cook the pasta according to the package directions until al dente.

While the pasta is cooking, heat a small dry skillet over medium-low heat.

Add the cashews and toast for a few minutes, stirring frequently, until they're lightly golden and fragrant. Watch them carefully as nuts can burn quickly.

Remove from the skillet and allow to cool slightly.

Finely grate the Parmesan.

Add the parsley, toasted cashews, Parmesan, lemon juice, olive oil, and salt to a food processor or blender.

Blend until you have a pesto-like consistency. If the mixture seems too thick, add a little more olive oil or a tablespoon or two of pasta cooking water.

Before draining the pasta, reserve a little of the cooking water.

Drain the pasta and toss with the parsley pesto until evenly coated. Add a splash of the reserved pasta water if needed to help loosen the pesto and coat the pasta.

Serve immediately with extra grated Parmesan on top.