Ingredients

1 bunch watercress, tough stems removed (about 5 1/2 cups), divided

2 tablespoons toasted pine nuts

Zest of 1 lemon

1 clove garlic, chopped

3 tablespoons extra-virgin olive oil

Coarse salt

Pinch of red-pepper flakes, or to taste

10 ounces farro spaghetti or whole-wheat spaghetti

Preparation

Pulse 5 cups watercress, pine nuts, lemon zest, and garlic in a food processor until coarsely chopped. Add oil and pulse to combine. Season with salt and red-pepper flakes.

Meanwhile, bring a large pot of generously salted water to a boil. Add pasta and cook until al dente. Reserve 1 cup cooking water; drain pasta. Return pasta to pot and stir in pesto. Add enough reserved pasta water, a small amount at a time, to coat pasta and make a light sauce. Season with salt and top with remaining watercress.