Orechiette with Pistachio Pesto

This recipe is courtesy of Lissa Dutton who made it for us over Christmas. Excellent dish.
Ingredients

1. 1 pound orecchiette
2. 7 ounces unsalted roasted shelled pistachios (1 1/2 cups)
3. 1/2 cup extra-virgin olive oil
4. 2 tablespoons chopped mint
5. 1 garlic clove, minced
6. 1/2 cup finely shredded pecorino cheese, plus more for serving
7. 2 scallions, cut into 2-inch lengths and julienned
8. Salt

Directions
1. In a large pot of boiling salted water, cook the pasta until al dente. 2. Meanwhile, in a food processor, pulse the pistachios until coarsely chopped. Add the oil, mint and garlic and pulse just to combine. Transfer to a pasta bowl, stir in the cheese and scallions; season with salt. 3. Drain the pasta, reserving 1/2 cup of the cooking water. Return the pasta to the pot. Add the cooking water and the pesto and cook over low heat, tossing, until coated, 1 minute. Transfer the pasta to the bowl and serve, passing extra cheese on the side.