On a non-stick pan, cook the spinach till they are completely soft and their water has evaporated.
To a blender, add all the ingredients including the cooked spinach and blend till you get a a creamy pesto.Taste and add more salt or more nutritional yeast based on your taste.
Before serving the pesto, warm it up in a pan with some pasta cooking water, then add the pasta, mix well, and serve with some grated lemon zest on top.
Store in an airtight container in the refrigerator for up to a week.