Prepare pasta, zoodles, or spaghetti squash. If using pasta, cook according to directions, reserving at least 1 cup of liquid.
In a food processor or blender, combine avocado, spinach, almonds, parsley, garlic, olive oil, and salt. Pulse several times. Add reserved pasta water or warm water, starting with 1/2 cup and adding more, pulsing after each addition, until sauce reaches desired consistency. Toss sauce with pasta and serve topped with parmesan cheese if desired.