Photograph: Jonathan Gregson
In a pan, bring the milk to the boil with the onion, bay leaf, cloves and thyme. Simmer for 10 minutes, then strain into a clean pan, discarding the flavourings.
Stir in the breadcrumbs and cook gently for 10-15 minutes or until thick. Season with a few gratings of nutmeg and salt. If you like a thinner sauce, you can pass it through a coarse sieve.
Get ahead: make the day before (can also be frozen), then reheat in a pan, add a little milk to thin if necessary.