In a small saucepan, warm the milk with the nutmeg, bay leaf, shallot and peppercorns. When bubbles form around the edge of the pan, remove from the stove.
Melt the butter in a large saucepan, remove from the heat and stir in the potato flour. Strain the milk and pour into the pan, blend well and return to the heat. Whisk briskly until the mixture comes to the boi