Add oil to a large frying pan over medium-high heat and sear the lamb in batches. Set aside. Add onions and garlic to the frying pan and fry until soft, about 7 minutes.

Add all stew ingredients (except butter beans) to a slow cooker. Stir and cook on high for 3-4 hours, or until the lamb is beautifully tender. When the stew is almost done add the butter beans and season liberally with salt and pepper.

Remove bay leaves and cinnamon quills before serving with hot buttered crusty bread (optional).