Begin by bringing a small pot of salted water to a boil. Chop the asparagus into 2-inch pieces before adding them to the boiling water. Blanch for about 5 minutes until the asparagus is bright green and slightly tender. Rinse under cold water and set aside.

In a separate large pot, fill with salted water and bring it to a boil. Add your choice of pasta and cook according to package instructions for al dente, usually about 8-10 minutes. Reserve 1 cup of starchy pasta water before draining.

In a blender, combine the blanched asparagus (reserving the tips), pistachios, garlic (if using), lemon juice, lemon zest, fresh parsley, olive oil, salt, and pepper. Blend until smooth and creamy.

Return the drained pasta to the pot over low heat. Add the asparagus pesto to the pasta, tossing everything together. Gradually mix in the reserved pasta water until you reach your desired creamy consistency.

Plate your pasta, coat generously with the pesto, garnish with the reserved asparagus tips and additional lemon zest. Serve hot.