Hi, I want to make Nigella's Devil's Food Cake (Kitchen, p253) but I don't have two sandwich tins. I am wondering if I can make the recipe and cook half at a time? Will half of the batter be OK standing while the other half is cooking? Also even if I were to buy another tin they won't both be able to sit on the same shelf in the oven so is it OK to have one on a higher shelf than the other? Should I rotate the tins halfway or do any other time adjustments? What option is best?
Unfortunately leaving a cake batter to stand for any length of time can have a detrimental effect on the finished cake. A cake usually rises due to a combination of air whipped into the batter, the leavening effect of eggs and in particular the raising agents in the recipe (here baking powder and bicarbonate of soda/baking soda). The raising agents usually start acting immediately and will only last for a fairly short period of time so if the cake batter is left to stand before baking then there is a risk that the raising agents will have expired by the time that the cake goes into the oven. The cake will then not rise as well and could be heavy or dense in texture. The oven should be fully preheated while the cake batter is being mixed and the batter should be cooked in matching pans.
Baking the cake layers on different shelves of the oven is usually possible for layer cakes but you will need to switch the pans around during baking. This needs to be done carefully as if the cake has not quite set and comes into contact with cold air then it may sink in the middle. As the baking time is around 30 minutes then we would suggest rotating the pans after about 20 minutes. But if the cake layers still look liquid in the centre after this time then don't rotate them and you may find that you just need to cook one layer for slightly longer than the other (they should be firm to the touch once fully baked and a cake tester should come out clean if inserted into the centre).
Also it is best to have 2 identical sandwich tins (cake pans) so that the cake layers cook evenly. If you use one sandwich tin and one deeper tin, or springform pan, then the baking time in the deeper tin will be longer as the sides of the tin tend to keep heat from the top of the cake and slows down the cooking slightly.