Preheat the oven to 180 degrees C. Line and generously butter a 20cm round, non-stick cake pan.
To make the filling, beat the egg yolks with the sugar till foamy and pale.
Add the cream cheese and yoghurt and mix well so that there are no lumps.
Now mix in the cocoa and flour and pour in the melted chocolate so that it is well incorporated into the mixture. Then add the Kahlua.
In a separate bowl, beat the egg whites until stiff and gently fold into the cake mixture.
Pour the mixture into the prepared pan and bake for 50-60 minutes till the cheesecake is just set. Switch off the oven, open the door and leave the cake in for an hour before transferring to a plate. Chill cake for upto 3-4 hours before serving.