Is it possible to freeze my chocolate sheet cake when it is completely iced? I want to start preparing party food well in advance.
Nigella's Chocolate Sheet Cake is slightly unusual as the chocolate icing is poured over the cake while it is still warm. The icing is partly absorbed by the cake, giving a fudgy texture and a rich chocolate flavour. Usually we prefer to freeze sponge cakes without any icing or frosting on as it is easier to wrap them tightly (which helps to preserve them in the freezer) and to prevent the icing being smudged or squashed. The cake keeps well for 5 days if the tin is tightly wrapped in clingfilm and left in a cool place, so you may find this helpful for your party planning.
It is possible to freeze the chocolate sheet cake with the icing on, however we would mention that very ocassionally the icing can turn slightly soft when the cake is defrosted if too much condensation forms during the freezing and thawing process. If the cake is for a party we suggest leaving the cake in its tin and when completely cold cover the tin tightly in a double layer of clingfilm and a layer of foil. Freeze for up to 1 month. Unwrap the tin and leave to thaw at room temperature for about 4 hours.