25 g (1 oz) Parmesan cheese, grated, plus extra to serve
Cook the pasta in a large saucepan of salted boiling water according to the pack instructions until al dente.
Meanwhile, make the walnut paste. Place the walnuts in a frying pan and dry-fry for a couple of minutes, shaking the pan every now and again, until toasted. Reserve some of the nuts for garnish and place the remainder in a food processor or blender. Add the cream, garlic and Parmesan, then whizz together to form a smooth paste.
Drain the pasta, reserving a little of the cooking water, and return to the pan. Stir in the walnut paste, adding a little cooking water to loosen if needed. Season well.
Spoon into serving bowls and serve scattered with the reserved walnuts, basil and extra Parmesan.