Stud the onion with the cloves and place in a saucepan. Add the bay leaf and the peppercorns and then pour over the milk.
Bring up to the boil and then switch the heat off and leave to infuse for 3 hours.
Remove the onion, bay leaf and peppercorns and add half the butter. Season with salt and pepper and then add the bread crumbs. Return to the heat and gently cook until the breadcrumbs have absorbed the milk and the mixture is soft and creamy. Now you can leave this over night or indeed freeze it. When you reheat it for the table, as it should be served warm, beat in the rest of the butter and then taste, adjust the seasoning if necessary and then serve.