Why Did The Custard For The Vin Santo Ice Cream Split?

Our answer

Nigella's Vin Santo Ice Cream With Cantuccini takes the traditional Italian after-dinner treat of cantucci cookies dipped in vin santo and turns it into a frozen dessert with vin santo ice cream. The ice cream is made in the traditional way, with a custard base.

The alcohol appearing to split out of the custard is most likely to have been caused by the mixture being overheated at some point. This could happen at a couple of points in the recipe. First if the vin santo is very hot when it is added to the egg yolks then it can cause them to slightly scramble, which means that the finished custard will not be smooth and amalgamated. It can help to cool the vin santo slightly first and also to add just a small amount intially to the egg yolks, whisking it in (sometimes called "tempering" the eggs), before adding the rest in a thin stream whilst whisking constantly. Second, when the custard is being cooked you need to keep the heat low to medium-low and keep stirring patiently and continuously until the custard thickens. As Nigella notes, have a sink of cold water standing by so that you can dip the base of the saucepan into the cold water to stop the mixture from overheating, if it looks like the custard is splitting.