Directions

1. Bring 4 qt. hot water and 1 Tbsp. salt to a boil in a covered 6- to 8-qt. pot. Meanwhile, prepare pesto. Put pine nuts in a small frying pan over medium heat and cook, stirring constantly, until golden brown, 3-5 minutes. Pour nuts onto a plate and let cool.
2. Set aside a few basil leaves for topping cooked pasta if you like. Put remaining basil, cooled pine nuts, garlic, lemon zest (if using), lemon juice, 1/2 tsp. salt, and the pepper in a food processor. Pulse to create a coarse puree, scraping down inside of bowl as needed. Slowly add olive oil with the motor running. Add Parmesan and process again until smooth. Scrape pesto into a small bowl, cover, and set aside. Set the food processor aside; do not rinse it out.
3. When the water comes to a boil, add pasta and cook, stirring occasionally, until barely tender to bite (al dente), about 11 minutes. Scoop out and reserve 1/2 cup cooking water. Drain pasta and return to the cooking pot.
4. Pour reserved pasta cooking water into the food processor (which still has bits of pesto in it) and pulse so all the remaining pesto disperses into the water. Pour water over pasta along with the pesto and stir with a rubber spatula until pasta is coated evenly.
5. Transfer pesto pasta to a large serving bowl. Serve immediately, with reserved basil leaves on top if you like.