Prepare the pistachio pesto by placing the basil, extra-virgin olive oil, pistachios, garlic and a little salt and pepper in a food processor. Blitz until smooth. Add the Parmesan and pulse until a thick consistency is reached. Chill until needed.
Bring a large saucepan of salted water to the boil and cook the spaghetti until 'al dente'; usually 8-10 minutes. Drain and toss with tablespoons of the pesto.
Spoon onto serving plates and garnish with the shaved Parmesan before serving.