I followed the recipe for Nigella's Italain Christmas PUdding Cake, but the mixture would not thicken. Eventually I beat it for so long it separated and I had to throw it all away. Why did it not work? I used all the ingredients as described and Elmlea double cream. Thanks
Nigella's Italian Christmas Pudding Cake (from Nigellissima) is similar to a tiramisu, with layers of thinly sliced pannetone sandwiched with a mixture of whipped eggs, mascarpone and cream that has been studded with marrons glaces.
The recipe uses double cream (heavy cream for the US and whipping cream for those that can't get double cream) and we suspect that the problem lies in using Elmlea. Elmlea is a British product and although it appears to be cream (it is labelled as single or double and is in a container that is similar to a cream container) it is in fact not cream. It is a "dairy cream alternative" that is made from vegetable oils and buttermilk.
In our experience the "double" form of Elmlea will whip but it can take quite a bit longer than double cream to whip properly. This may be due to the lower fat content (it has about 30% less fat than double cream). Our suspicion is that when it was mixed with the other ingredients it may have become more difficult to whisk, and if you whisk mascarpone for too long it will start to separate.
We would suggest using dairy double cream next time. If you have to use a dairy cream alternative then it may be better to mix together the eggs, mascarpone and all of the other ingredients then whip the dairy cream alternative until it makes soft peaks and fold this into the mascarpone mixture just before using.