I made Nigella's Salted Caramel Sauce yesterday. It tasted divine.but after storing it in the fridge the fats separated and formed a layer. I had to remove the layer to get the sauce out and the quantity reduced in half. I followed the recipe properly while making it so I could not understand what went wrong. Any advice?
Sometimes a caramel sauce will separate, whether it is made via the classic method of making a caramel before adding butter and cream or via Nigella's speedier method. Usually this happens because the sauce has gone through a quick temperature change which has caused the fats to separate from the sugars. It could be that the sauce was too warm when it was transferred to the fridge.
However it is still fine to use as the sauce should re-emulsify when it is warmed. If you can't get the sauce out of the container then warm the sauce gently until it just softens enough to remove it from the container. You can use either a microwave (using very short blasts) or by standing the container in a bowl of warm water. We would suggest being very careful if you have used a glass container as sudden changes in temperature can shatter the glass.
Warm the sauce gently in a saucepan. If the sauce still doesn't come together then carefully whisk in some very hot water, a tablespoon at a time, until the sauce re-emulsifies.