Clean and wash the leek and cut into fine rings. Peel, wash and dice the potatoes. Put both in a large pot and pour 1 1⁄2 l water on them. Bring to the boil, stir in broth and cook covered for about 25 minutes until the potatoes are crumbled.
For the croutons, wash the parsley, shake dry, remove the leaves and chop. Toast the bread in a toaster. Cut into small pieces. Heat butter in a frying pan. Fry the croutons and parsley.
Pour cream into the soup and simmer for about 2 minutes. Puree the soup with a hand blender. Season to taste with salt and pepper. Serve sprinkled with croutons and parsley.