Step 1

Bring a large pot of heavily salted water to a boil. Meanwhile, make the pesto.

Step 2

Make the pesto: Layer about half the spinach into the bowl of a food processor or blender. Scatter the walnuts, Parmesan, garlic, lemon juice, and salt over the spinach. Pulse until the ingredients are incorporated and the spinach is coarsely chopped. Add the remaining spinach. With the motor running, stream 3 tablespoons of the olive oil into the spinach until it is saucy. Scrape down the sides and give it a taste. Add more salt or lemon juice to taste. If you'd like a richer pesto, stream in the remaining tablespoon of olive oil.

Step 3

Make the salad: Add the orzo to the water and boil until al dente, about 8 minutes or according to package directions. Drain and transfer to a large bowl. Immediately add the pesto, feta, olives, shallots, and lemon juice and stir gently to combine while the pasta is still warm. Taste and season with more salt, pepper, or lemon juice as needed.

Step 4

Let the salad cool and then refrigerate for up to a week. The flavors improve by the second day.