Pour the milk into a small nonstick pan. Peel and chop the onion, and peel the garlic. Add both to the pan with the cloves and bay leaves, and season well.
Tear the bread into chunks. Bring the milk mixture to the boil, then add the bread and simmer, stirring occasionally, over a low heat for 5 to 10 minutes until the onion is cooked.
Carefully remove the cloves and bay leaves, then transfer the sauce to a blender and blitz till puréed.
Return to the pan, adjust the seasoning and continue to gently cook, stirring constantly, for a few minutes to thicken. Stir in the butter and cream to finish.