Whip the cream cheese with the sugar until soft and homogeneous. Every once in a while stop and use a spoon to bring down the un-mixed parts that stick on the bowl and at the bottom.
Add the sour cream, vanilla essence and salt and mix again.
Lower the speed of the machine to minimum and add the egg. Mix it in on low speed so as not to add air into it.
Fill the muffin paper cases with the mix and take to a preheated oven at 180C in a tray with boiling water. The water should go halfway up the cheesecakes.
As soon as it goes into the oven, lower the temperature to 150C.
Cook for 15min or until it's barely shaking or not shaking at all if you wiggle the mould gently.
Wait for them to cool down completely and then put in the fridge for at least 2 hours.