In a large pot, heat oil over medium heat. Add onions, garlic, leeks, and celery. Saute for ~8 minutes.
Add all remaining ingredients except for the spinach and cashew butter to your pot. Bring soup to a boil and then lower to a simmer. Cook for about 20 more minutes or until potatoes are tender.
Turn of heat. Remove thyme from soup. Add 3-4 cups of soup to a blender. Add cashew butter to the blender and blend until smooth. Pour blended soup back into the soup pot. If using an immersion blender, add cashew butter to soup, stir until combined and then blend to desired thickness.
After your soup is blended add spinach and stir until wilted.
Let soup cool and serve!
Notes
This makes about 2-3 servings of soup.If you want to quickly soak your cashews boil them for 15 minutes. Otherwise they should be soaked for at least 4 hours.If you want your soup to be less chunky blend more of the soup, if you want it to be less chunky blend less.