Chicken Liver & Foie Gras Parfait

Chicken livers need to be treated carefully if they are not to become dense and strongly flavoured when cooked. The standard chicken liver terrine is too often presented as a solid chilled block, but who likes the idea of chicken liver ice-cream? This much lighter variation on the theme incorporates some duck foie gras, which gives a luxurious dimension. The strength of taste is moderated by incorporating a high percentage of butter and the mousse is cooked at a very low temperature, until