Put the milk in a saucepan, and heat it on a low heat with the onion, clove, bay leaf and thyme for 10 minutes, allowing the flavours to infuse.
Chop the bread into small pieces. Strain the milk through a sieve and place back onto the heat, add the bread pieces and cook until thickened.
Season with salt and pepper, then serve. It's common for bread sauce to be served at room temperature, like many condiments are.