- 1 lb dried spaghetti
- 1/3 cup chopped fresh parsley
- 3 to 4 tablespoons chopped fresh sage
- 1 garlic clove, chopped
- 1 teaspoon salt
- 1 cup walnuts, toasted and cooled
- 1/3 cup olive oil
- 1/3 cup grated Parmigiano-Reggiano (3/4 oz) plus additional for serving
- 1/4 teaspoon black pepper
- Cook spaghetti in a 6-quart pot of boiling salted water until al dente.
- While pasta is boiling, blend parsley, sage, and garlic with salt in a food processor until finely chopped. Add walnuts and pulse until finely chopped. With motor running, add oil in a steady stream. Turn off motor, then add 1/3 cup cheese and pepper and pulse to combine.
- Reserve 1 cup cooking water, then drain pasta in a colander. Thin pesto with reserved cooking water in a serving bowl, then add pasta and toss to combine. Sprinkle with cheese before serving.