Rinse the beans. Soak in plenty of water overnight.
Drain the beans. Peel onions and garlic and cut them into large pieces. With beans and bay leaf in a pot 3 finger-high cover with water. Simmer covered for about 45 minutes. Stir more often and skim off the foam.
Remove laurel. Clean, wash and chop the spring onions. Add oil, thyme, salt and pepper to the beans and puree everything in a blender until creamy. Garnish with fried parsley if necessary.