Boil the potatoes in the normal way. Strain them and pass through a coarse sieve or mouli grater so that you have a pile of almost powdered pommes.
Heat the milk and melt the butter in it. Add the nutmeg and many twists of the pepper mill.
In a large bowl beat the eggs. Add the potatoes and whisking as for mayonnaise add the milk slowly. The result is only just short of a liquid