|Parsley Pasta with Toasted Walnut Sauce
2 cloves garlic, coarsely chopped
1/4 cup toasted walnuts, coarsely chopped
2 cups packed fresh parsley leaves, coarsely chopped
1/4 cup grated Parmigiano-Reggiano
3/4 cup mild walnut oil or extra-virgin olive oil
1 pound spaghetti
For the sauce: Using a mortar and pestle, crush the garlic, walnuts, and a large pinch of salt together. Add the parsley a handful at a time and continue crushing and grinding with the pestle to make a fine paste. Add the cheese, crushing it into the paste. Drizzle in the oil in a thin, steady stream, stirring constantly with a wooden spoon. Season the sauce with salt. This makes about 1 cup sauce.
To make the sauce in a blender (or food processor): Grind the garlic, walnuts, a large pinch of salt, parsley, and 1/2 cup of the oil in the blender until smooth. Transfer the sauce to a bowl and stir in the cheese and the remaining oil.
Season the sauce with salt.
Cook the spaghetti in a large pot of boiling salted water over medium-high heat until just cooked through, about 12 minutes. Drain the pasta, reserving 1/4 cup of the cooking water. Toss the pasta in a large bowl with the sauce, loosening the sauce with some of the reserved cooking water. Serve with grated Parmigiano-Reggiano, if you like. Serves about 6