The beating is done over simmering water so that the egg yolks cook as they thicken into a light, foamy custard. The mixture must not get too hot during cooking or it will become grainy. If it begins to feel warmer than body temperature, remove the pan briefly from the heat, beating continuously, until the mixture cools. Then return the pan to the heat and continue cooking. Zabaglione may be served warm or cold. A cold one is beaten off the heat until cooled.
Traditional zabaglione must be made just before serving. The warm froth can be served as a dessert by itself or as a sauce over cake, fruit, ice cream or pastry. They may also be used for sweet or savoury gratins. Cornflour is sometimes added for stability.
