Linguine with Toasted Walnut Pesto

From The Four Seasons of Pasta - Barilla

1/2 C walnuts
2 C tightly packed bail leaves
1/4 C grated Parmigiano-Reggiano cheese
1 garlic clove, chopped
2/3 C reduced-sodium chicken broth
1/3 C extra-virgin olive oil
1 box (16oz) Barilla linguine
1/3 C pasta-cooking water, reserved

Spread the walnuts in a small skillet and heat over medium to medium-low heat, stirring often, until walnuts are lightly toasted, about 4 minutes. Remove from heat.
Combine the walnuts, basil, cheese and garlic in food processor. Process until mixture is finely chopped. Add the chicken broth and process until pureed. With the processor running, add the olive oil in a thin steady stream until blended and smooth.
Meanwhile cook the pasta in plenty of boiling salted water until firm to the bite, according to package directions. Ladle out 1/3 cup of the pasta-cooking water. Remove from the heat and add 1 cup cold water to stop cooking; drain.
In a large bowl, toss the pasta with the pesto and the reserved pasta-cooking liquid until blended. Serve at once.