Pulse the crushed garlic clove in a food processor until finely chopped.

Add parsley and basil, pulse until chopped, then while the food processor is running, slowly add the olive oil in a steady stream.

Add ¼ teaspoon salt, pulse, then taste and adjust. The pesto will be salty from the pistachios and the salt, but not too salty. You can always add more salt to the pesto later, or season the final dish (which may have additional salt from the cheese and other ingredients).

Place zucchini in the bottom of the colander you will use to drain the cooked pasta.

In a pot of salted boiling water, cook pasta until al dente. Drain pasta into the colander with zucchini. Shake the colander to drain out as much water as possible, and give the zucchini extra time to heat.

Pour pasta and zucchini back into the pot in which you cooked it, and add baby spinach.

Toss pasta, zucchini, and baby spinach with Pistachio Pesto in the pot until everything is well-coated. Add feta cheese and very gently toss. Plate, then sprinkle with additional feta, lemon juice, and lemon zest if using.