Add the basil, green onions, garlic, lemon juice, salt, pepper and olive oil to form a pesto. Add the milk on top of the pesto and continue blending until the sauce is completely smooth and creamy. Set aside.

Bring a large pot of well-salted water to a boil over high heat. Cook the pasta until al dente, about 5 minutes, according to the package directions. Drain and rinse with cold water. (if using traditional pasta, drain, but do not rinse),

Add the pasta back to the pot along with pistachio sauce over medium heat, stirring frequently, until the pasta is warmed through and well combined with the sauce, 1 to 2 minutes.

Sprinkle the reserved pistachios on top, garnish with extra basil and serve immediately.