Nutella Cake Sinking

Our answer

Nigella's Nutella Cake (from Domestic Goddess and on the Nigella website) is a flourless chocolate cake. As there is no gluten in the cake it will tend to sink back in the centre as it cools and this is common with most flourless chocolate cakes (which are sometimes called "fallen chocolate cakes"). If you exclude the frangelico or rum from the cake then this does not make a difference to the way that the cake bakes.

If the cake is collapsing dramatically then it may be that the egg whites are being whisked too much. The whisked egg whites are the only leavening (raising agent) in the cake. If the whites are whisked too much then the cells walls of the white are stretched too far and will break during baking, which will cause the cake to sink more. You should whisk the whites until they just stand up in stiff peaks. As it can be very easy to go from stiff peaks to over-whisked whites it is a good idea to check very frequently when whisking, to see what stage the whites are at.