Bring a large pot of heavily salted water to a boil.
While the water heats, combine the arugula, pistachios, Parmesan, garlic, lemon juice and olive oil in a food processor. Blend until smooth but still slightly textured. Season with salt and pepper to taste.
Cook the Stella pasta until just al dente, about 5–7 minutes. Taste for texture—you should always cook pasta to feel, not just the clock.
Using a spider or slotted spoon, transfer the pasta directly into a large bowl with the pesto, bringing along a little of the salty, starchy pasta water.
That starchy pasta water is liquid gold. It helps emulsify the pesto, creating a silky sauce that coats every tiny star without becoming heavy.
Toss gently until every piece of pasta is evenly coated. If needed, add another splash of pasta water to loosen the sauce.
Finish with extra shaved Parmigiano Reggiano, chopped pistachios, fresh basil and a drizzle of your best olive oil.
This dish is equally delicious served cold. Allow the pasta to cool completely, then refrigerate for at least an hour before serving. Finish with fresh lemon zest, extra pistachios and a drizzle of olive oil just before serving for a refreshing summer pasta salad that's perfect for entertaining or bringing to the beach.