Hello, Is it necessary to bake the Chocolate Cheesecake in the roasting pan with boiling water? Or can I bake it without the roasting pan and the boiling water?
Nigella's Chocolate Cheesecake (from Feast and on the Nigella website) and many of her other cheesecakes are baked in a roasting pan which is half-filled with boiling water. This water bath is also known as a "bain-marie". The purpose of a bain-marie is to keep the ingredients being cooked at a low, consistent temperature and it is a very gentle form of cooking.
It is important to cook the cheesecakes in a bain-marie as it is the eggs in the cheesecake filling that will set the mixture. As the filling is in essence a type of egg custard, it requires very gentle cooking otherwise there is a risk that the eggs will over-cook. Whilst some recipes will not use a bain-marie for cheesecakes, you have to be very careful with the oven temperatures and cooking times and in our experience cheesecakes cooked in a bain-marie cook more evenly and have a much smoother texture. So we believe that using a bain-marie is worth the extra effort.