To make the sauce: While the pasta is cooking, combine the cashews, water, nutritional yeast, lemon juice, garlic, mustard, Tabasco, salt, and cayenne in a blender. Blend at high speed for about 1 minute, until smooth, scraping down the sides of the blender halfway through, if necessary. Taste for seasoning, adding more salt and/or cayenne, if needed. You can also add an extra splash of water, if you prefer a thinner sauce.