Cook Spaghetti according to directions on package.
Whilst the Spaghetti is cooking, prepare pesto.
Combine all ingredients for the pesto in a food processor and process until almost smooth. Little bits of unprocessed Cashew is fine, as it adds texture to the sauce.
Once blended, transfer to large mixing bowl.
Drain pasta when done and reserve cooking water. Combine pasta with pesto and toss till noodles are coated well. Add about 1/2 a cup of reserved pasta water and toss, to loosen up the pesto. Serve warm.