Bring all ingredients to room temperature. Place oven shelf in the centre of oven and preheat to 190 degrees C. Wrap the outside of a 23cm springform pan with foil. Generously butter the inside of the pan.
In a large bowl, beat cream cheese and butter until smooth. Mix in sugar and cornflour. Blend in sour cream and cream. Add amaretto and vanilla esence.
Stir in eggs and egg yolk one at a time, mixing thoroughly between each addition.
Pour mixture into prepared springform pan. Place inside another pan at least 2.5 cm wider than the springform pan and add warm water to the outer pan to create a water bath for the cake (this prevents cracks in your cheesecake). Bake in preheated oven on the centre rack for 70 minutes.
Turn oven off and allow to cool with oven door open for 1 hour. Then remove cake from water bath and chill at least 3 hours before removing from springform pan.