Sort the watercress and remove the stems. Wash it, then chop it coarsely.
Peel and finely chop the potatoes. Do the same with the onion.
Gather all the ingredients in a saucepan, add the bay leaf, salt and pepper.
Pour in the stock and add the butter piece by piece.
Bring to a boil, cover, lower the heat and simmer gently for 30 minutes.
Place in a blender after removing the bay leaf.
Put the preparation back on the heat, add the crème fraîche and the nutmeg without stopping stirring.
Just before serving, crush a crunchy Sigdal Rye and Spelt Bran on each plate.