Bring a large pot of salted water to boil. (This water should be generously salted and taste like the sea)
While the water is coming to boil, make the pesto. Process pistachios, nutritional yeast, salt, red pepper flakes, and black pepper in a food processor until the pistachios are broken down into a coarse flour like texture. Add basil leaves and process until well broken down. With the motor running, slowly stream in lemon juice and olive oil and process until oil is emulsified and pesto is mostly smooth, with just a few speckles of green.
When the pot of water comes up to a boil, add 8 oz of pasta and cook until al dente (follow package instructions). Reserve ½ cup pasta cooking liquid, then drain. Immediately toss the pasta vigorously with pesto sauce and a little splash of pasta cooking liquid. Add more pasta cooking liquid if needed. Stir until pasta is glossy, creamy, and well coated with sauce. Season with salt to taste. Serve immediately.