Check that your tin is watertight by pouring water into it. If it leaks slightly, you can make a ‘cradle’ with tin foil. To do this, put a piece of tin foil on the work surface and then place the tin on top. Bring the tin foil up over the edges a bit and squeeze it all in tightly to ensure it doesn’t let any water in or any cheesecake mixture out. Line the base and sides of the cake tin with baking parchment. Place the roasting tin and baking sheet into the oven.
Put the cream cheese in a large bowl with the butter, caster sugar, lemon zest and vanilla and mix together well with a wooden spoon or spatula. Add the eggs and the crème fraiche and stir so that the mixture is just combined. It is best not to overbeat the mixture at this stage, or you will end up with lots of air bubbles in your finished cheesecake. Pour this mixture into the lined tin and then carefully place it in your heated bain-marie.
Once the cheesecake is cooked, turn the oven off and leave the cheesecake to cool down in the oven for about 90 minutes with the oven door slightly ajar. This helps to stop the cheesecake from cracking as it cools down slowly. When you are sure that it has cooled down completely, remove from the oven and then carefully release it from the tin, gently peeling the baking parchment from the sides of the cake. Slide the cheesecake onto a serving plate and serve.