Hi. I am planning on baking an 8 egg sponge cake in the shape of a castle and would really like to make Nigella's Buttermilk Birthday Cake recipe as I have been hearing good things about it and that it holds the weight of icing really well. However I can't find quantities anywhere for such a large cake, or cooking times. Any help would be really gratefully received. Thanks
Nigella's Buttermilk Birthday Cake (from Domestic Goddess) is a very popular cake. However the recipe is for a 23cm/9 inch square tin or two 20cm/8 inch round tins. If you are using a fairly shallow castle shaped tin (such as the Wilton Enchanted Castle Cake Pan) then you would need to make a double quantity of the cake batter for the pan and bake at 180c/350F for about 45 minutes. You need to fill the pan 1/2 to 2/3 full and may have a little batter left over but this could be baked as cupcakes for around 20 minutes.
Unfortunately it is difficult to scale up cake recipes and we are unable to advise on an 8 egg version of this cake. Also the amount of batter for an 8 egg sponge can vary enormously depending on the recipe you use, as some recipes such as Victoria sponge will yield different quantities to a recipe containing extra liquid such as buttermilk. It is also very difficult for a domestic baker to bake a sponge cake much larger than 25cm/10 inches in diameter as you start to get problems with the cake not cooking in the centre or being dry on the outside, and larger sponge cakes can tend to collapse in on themselves.