Preheat the oven to 175 C. Line the bottom of a 22cm spring-form pan with baking paper.
Cook the cream cheese and milk in a small saucepan over medium heat stirring occasionally until cheese is melted. Remove from the heat and set aside.
In a medium bowl, beat egg yolks and half of the sugar until light and fluffy. Fold the cream cheese mixture into the yolks. Sift in the flour and cornflour and stir until blended.
In a separate bowl, using clean beaters, whip egg whites with cream of tartar to soft peaks. Gradually sprinkle in the remaining sugar and continue whipping to stiff peaks. Fold egg whites into the cream cheese mixture. Pour into the prepared cake pan and place the cheesecake in a baking dish. Pour in water until halfway up the sides of the baking dish. Bake for 20 minutes, then reduce the heat to 150 C and continue baking for 15 more minutes. Let the cake cool before removing from the pan.
Run a knife around the outer edge of the cake pan, and invert onto a plate to remove the cake. Peel off the baking paper and invert onto a serving plate so the top of the cake is upright again.