Penne with Pesto, Potatoes & Green Beans

Ingredients
For the pesto:
- 1 1⁄2 cups lightly packed fresh basil leaves
- 3 Tbs. pine nuts
- 1 garlic clove, coarsely chopped
- 1⁄2 tsp. kosher salt
- 1⁄3 cup extra-virgin olive oil
- 1⁄4 lb. Parmigiano-Reggiano cheese, freshlygrated
- Kosher salt for cooking the vegetables andthe pasta
- 1⁄2 lb. small red potatoes, peeled and slicedabout 1⁄4 inch thick
- 1⁄2 lb. young, thin green beans, stem endstrimmed
- 1 lb. dried penne
- 1 Tbs. unsalted butter, at room temperature
Directions
Make the pestoPut the basil, pine nuts, garlic and salt in a large mortar. Using a pestle, and working in a circular motion, grind the ingredients together until a dense, thick green paste forms. This could take several minutes to do, but don't be discouraged. Slowly drizzle in the olive oil while stirring continuously with the pestle until a thick, flowing sauce forms. Transfer the mixture to a bowl and then use a spoon to stir in the cheese. Taste the pesto; it should taste primarily of fresh basil with accents of garlic, nuts and cheese. If you feel it tastes bland, stir in more cheese or salt until the flavors are nicely balanced. Keep in mind that the flavor will be diluted once it is mixed with the pasta and vegetables.
Cook the vegetables
Preheat an oven to 200°F and place a large, shallow bowl and individual plates in the oven to warm. Bring a large pot three-fourths full of water to a rolling boil and add about 2 Tbs. salt. Add the potatoes and green beans and cook until tender, about 5 minutes. Use a large slotted spoon to transfer the potatoes and beans to the warmed large bowl. Cover the bowl lightly with aluminum foil to keep the vegetables warm.
Cook and drain the penne
Bring the water back to a rolling boil, add the pasta all at once and stir it gently. Let the pasta cook, stirring occasionally, until it is tender but still slightly chewy (al dente), 7 to 9 minutes. Transfer 2 ladlefuls of pasta-cooking water to a heatproof container; youll use it to adjust the consistency of the dish when you toss it. Pour the pasta into a colander to drain, then shake the colander just once to remove some of the remaining water. The pasta should still be moist.
Toss the penne with the sauce and vegetables
Add the drained pasta to the bowl with the vegetables and then add the pesto. Using a wooden spoon or spatula, stir and toss the pasta and vegetables until they are well coated with the sauce. If the mixture looks dry, add a little of the pasta-cooking water and mix again. Add the butter and toss to coat evenly.
Serve the dish
Using a large serving spoon, divide the sauced pasta and vegetables evenly among the warmed plates. Serve immediately. Serves 4 to 6.
Chefs Tip: To keep pesto a vibrant green, many chefs add a couple tablespoons of flat-leaf parsley leaves to their formula. Parsley doesn't darken the way basil does when it is pounded or cut.
Adapted from Williams-Sonoma Mastering Series, Pasta, Noodles & Dumplings, by Michele Scicolone (Simon & Schuster, 2005).