Peel and chop the potatoes into cubes.
Finely chop the garlic, the cleaned leeks and the celery.
Melt the butter in a large saucepan, add the vegetables and gently cook about 10 minutes or so until the butter is absorbed, but don't allow to brown.
Add ¾ of the stock and simmer until the potatoes are soft, about 15 minutes.
Puree the soup in two batches in a blender and add the balance of the stock.
To serve, mix the croutons, scallions and parsley together and mound a large spoonful on top of each bowl.
