Chocolate Cake Overflowed

Our answer

There are a few reasons why cake batter may overflow from the tins while baking but one of the most common reasons is that the tins are too small or too shallow. The cake batter for both cakes should be divided between two 20cm/8-inch diameter sandwich tins/cake pans and usually these are about 5cm/2 inches deep. So do check the size of the pans that being used.

Another common reason is that there is too much raising agent in the cake batter. Nigella's Old Fashioned Chocolate Cake recipe (from Feast and on the Nigella website) uses 1 teaspoon baking powder and 1/2 tespoon bicarbonate of soda (baking soda) with plain (all-purpose) flour. The Chocolate Fudge Cake (from Forever Summer and also on the website) uses 2 teaspoons baking powder and 1 teaspoon bicarbonate of soda. The raising agents should be measured accurately, preferably with a 5ml measuring teaspoon and a 2.5ml half teaspoon. The measured spoonfuls should also be flat, not heaped. Also if self-raising flour was instead of plain flour the there would also be too much raising agent as self-raising flour already contains baking powder.