Heat the oil in a saucepan and fry the onion until soft but not coloured. Add the parsnips, bay leaves, milk and stock and bring to the boil and summer gently until the parsnip is very soft. You might have to add some more stock while cooking; I found it evaporated rather quickly making the soup eventually too thick, so adding extra stock will keep it liquid enough. When soft, remove the bayleaves and drain off, but keep the liquid. Put the parsnips in a blender and whizz them until pureed and add some of the cooking fluid while whizzing until you have a good consistency but not too thick. At this point you can add some double cream to it, to make it a little creamier.
For the parsley puree and cream, blanch the parsley in boiling salted water for 30 secs, then refresh in iced water - this keeps the green colour. Repeat this process twice. Keep in mind that the mountain of parsley you think you have will diminish to almost nothing when blanched.. :) Bring the double cream to the boil. Squeeze out all the water from the parsley, then put in a blender and while slowly adding the hot cream whizz until it is as smooth as you can get it. Cool. Fold a little of the parsley puree through the whipped cream until nice and green. Season and chil. Keep the remaining puree for serving.
For the garnish; heat the oil and toss in the cubes of bread and toast until golden. Drain on kitchen towel if needed and add to the soup.