Begin by peeling and trimming the parsnips: cut out any woody centre bits, then cut the parsnips up into approximately 1 inch (2.5 cm) chunks.
Then place them in a fan steamer over some simmering water, sprinkle with salt, and steam - covered - for approximately 10 minutes or until the chunks are tender when tested with a skewer.
Now strain the parsnips (reserving the steaming liquid), put them in the bowl of a processor and purée them along with the crème fraîche, until they're completely smooth, and add the nutmeg and seasoning. If you think the mixture is too dry, mix in 1 or 2 tablespoons of the steaming water. Then return the parsnip purée to the saucepan and stir with a wooden spoon over a medium heat for about 5 minutes until piping hot.