Instructions: Put the arugula, garlic, walnuts and olive oil into the container of a food processor or blender and puree until smooth and creamy. Add 1 of the tomatoes, peeled, seeded and chopped and puree.

Turn the mixture into a bowl, season to taste with salt and pepper, and set aside. (The sauce can be made up to 1 hour in advance.)

Bring 4 quarts of water to a rolling boil in a large pot.

Meanwhile, cut each of the remaining 3 peeled and seeded tomatoes into small cubes and drain well.

When the water comes to the boil, stir in 1 1/2 tablespoons of salt and add the spaghetti. Stir it again and cook the spaghetti until al dente, or just tender, stirring frequently.

Put the butter in the bottom of a large bowl with 1 tablespoon of the sauce.

When the pasta is done, reserve 1 cup of the hot cooking water. Drain the spaghetti lightly and turn it into the bowl. Add half the sauce and the tomatoes and toss. Add the remaining sauce and tomatoes and gently toss. If necessary, add a little of the hot water and toss again if the sauce is not blended thoroughly or the pasta has dried out. Serve immediately and pass the pecorino or Parmesan cheese.

Serves 6 as a first course, 4 as a main
course.

If you would like to email yourself the recipe for later use, or share the recipe with your friends or family, enter the email addresses below and this recipe will be emailed to you and others as well.