Sour Cream Topping For London Cheesecake Did Not Cook Properly

Our answer

Nigella's London Cheesecake (from HOW TO BE A DOMESTIC GODDESS) is a baked cheesecake that has a traditional cream cheese filling and a thin top layer of sour cream to provide some contrast. The sour cream is added in the last 10 minutes of baking.

It is difficult to tell exactly what is wrong without a more detailed description, but the sour cream layer should thicken as the cheesecake cools and chills in the fridge. If the top of the cheesecake was not quite set when the topping was added then it is possible that some of the sour cream has sunk into filling and this would give an uneven surface. Make sure that the top of the cheesecake has set enough to be able to support the sour cream topping, even though the centre should still be slightly wobbly.