Start by making the pistachio pesto. You’ll only need ⅓ of the finished pesto for this recipe, so the remaining pesto can be stored in the fridge for another meal. Add the pistachios to a food processor and blitz until finely chopped. Add the Parmesan, fresh basil, olive oil, garlic and a pinch of salt, then blitz again until combined. Add around 50ml of water and blitz until smooth and silky. The water helps loosen the pesto and gives it a lighter, more silky consistency.