"French cream." Crème fraîche. Thick, slightly soured cream which has the great advantage of not separating when it is boiled. It is available in low fat forms which remain good consistency, both cooked and uncooked. It is made from cream curdled by the addition of bacteria and can be made at home by adding buttermilk or yoghurt to double cream (US: heavy cream), heating to 35ºC (90ºfahrenheit) and letting stand at room temperature until thickened.
