Mix together the cream cheese, sweetener, vanilla essence, orange rind and egg yolks in a bowl until smooth.
Whisk the egg whites until softly peaking, then fold a large spoonful into the cheese mixture to loosen it. Add the remaining egg whites and fold them in gently.
Pour the mixture into a buttered, 20 cm (8 inch) springform tin and level the surface. Bake in a preheated oven, 160°C (325°F), Gas Mark 3, for 30–35 minutes until well risen, golden brown and just set in the centre.
Turn off the oven and leave the cheesecake to cool for 15 minutes with the door slightly ajar. Take it out of the oven, leave to cool, then chill in the refrigerator for 4 hours. (The cheesecake will sink slightly as it cools.)
Run a knife around the cheesecake, loosen the tin and transfer to a serving plate. Dust the top with the icing sugar and caramelize the sugar with a cooks blowtorch. Serve within 30 minutes, while the sugar topping is still hard and brittle. Cut into wedges and arrange on plates with the orange segments.