Can anyone tell me how thick the Chocolate Sheet Cake is? I have cake tins that are slightly smaller but also shallower than the one in the picture. Worried about oven overflow.
The tin used by Nigella to bake the Chocolate Sheet Cake is 33 x 23 cm and has a depth of around 5cm (13 x 9 x 2 inches). The cake itself is not that thick and is approximately 2.5cm (1 inch) deep after baking. This gives a nice ratio of fudgy chocolate icing to sponge.
If you have a slightly smaller tin then we would suggest using one with a depth of at least 5cm (2 inches). The cake batter should not come more than halfway up the sides of the tin to prevent the cake overflowing as it bakes. If you are worried about the cake overflowing then it may be a good idea to put the tin on a baking sheet, to catch any drips. If the tin dimensions are very close to the ones suggested then the baking time should be the same, but as all ovens vary it is a good idea to check a couple of minutes earlier than the time given in the recipe. The cake should be risen, firm to the touch and a cake tester inserted into the centre should come out clean.