In a pot heat up 2 tablespoons of oil, add the bay leaf, allspice berries, onion and garlic, and cook gently for 3 minutes until softened, stirring often.
Add the beans, along with the liquid from the can, potatoes and half of the stock, cover, bring to the boil then lower the heat and simmer for 10 minutes (or until the potatoes are fully cooked).
Add the spinach, the rest of the stock, cover, bring to the boil again then simmer for 3 more minutes, stirring occasionally so all the spinach becomes incorporated into the soup. (It may seem like there is not enough liquid in the pot but do not be tempted to add more at this point as the spinach will release lots of water)
Remove from the heat, discard the bay leaf and allspice and puree the soup until smooth. Add pepper to taste and serve.
Notes
Beans: I used butter beans but any white bean variety would work. Remember to use the entire contents of a 400 g can of beans (i.e. beans plus the liquid).
Add the recommended amount of stock to start with - do not be tempted to add more even if it doesn't seem like there is enough. The spinach will release lots of water so after you've pureed the soup the consistency should be perfect. You can always add a splash of water once the soup is ready, if you like.
Serving suggestions: Serve as it is or with a dollop of yogurt, splash of cream of knob of butter (for non-vegan options). Delicious with homemade whole wheat breadsticks.
Storing: Refrigerate for up to 3 days. You may want to add a drop of water when reheating the soup.