The recipe below is adapted from „Made in Italy” cookbook by Giorgio Locatelli.
Start with preparing the walnut sauce.
Toast the walnuts in a hot pan (or in the oven) for about 3-5 minutes.
Wait until they cool down a little.
Crush the garlic clove in a mortar, add the walnuts and pound into a smooth paste, then stir in 2-3 tablespoons of olive oil, just enough to make a thick paste.
Blanch the tomato, peel, deseed and cut in small cubes.
Bring a large pan of salted water to the boil. Cook your pasta for about a minute less than the time given on the packet.
While the pasta is cooking, put the walnut paste into a medium pan with 1-2 tablespoons of olive oil and heat up gently. The paste should melt but not fry. Add some water from cooking the pasta to create a thick sauce. Add the chopped herbs and season with some salt and pepper.
Drain the pasta reserving some cooking liquid. Add the pasta to the pan with the sauce and toss well. Stir in the chopped tomato and check again for the seasoning. If you find the sauce too thick, add some of the reserved cooking water and stir properly.
Add the Parmesan, toss again and serve immediately.