Pour the milk into a saucepan and add the bay leaf, peppercorns, onion and mace. Heat gently to
just below boiling point. then remove from the heat, cover and leave to infuse for 10 minutes.
Sieve the milk into a jug.
Melt the butter in a separate saucepan. Sprinkle in the flour and cook over a low heat, stirring
constantly. for 1 minute. Remove from the heat and gradually stir in the milk. Return to the heat
and bring to the boil, stirring. Cook, stirring, until thickened and smooth. Season to taste with
salt and pepper.