Double these amounts to serve eight people. If you prefer it more "spirited", add a tablespoon of rum; adding one teaspoon of ground cinnamon wouldn't be a bad idea either.
With a wooden spoon, beat the yolks with the sugar until they turn almost white, then add the liquid, mix well and put over a high flame, whisking constantly and taking care not to let the mixture boil, because in that case it would curdle. Remove the zabaione from the flame the moment it begins to turn light and fluffy. In my opinion, it is best to use a chocolate pot.