Preheat the oven to 140°C. Grease and line a square tin with baking parchment.
Add the crushed biscuits to a bowl and stir in the melted reduced-fat spread. Press into the base of the tin. Pop into the fridge whilst you make the cheesecake and topping.
Add the raspberries, orange zest, orange juice and sweetener to a small saucepan and set on a low heat. Gently simmer for 8-10 minutes, until the raspberries have broken down and thickened.
Blitz with a stick blender to form a puree. Place a sieve over a bowl and pour the raspberry puree into the sieve to strain. You may need to gently press on the raspberry mixture to push it through the sieve. You should have a thick raspberry puree in the bowl and the seeds left in the sieve. Discard the seeds and leave the puree to cool while you prepare the cheesecake mixture.
In a mixing bowl beat together the cream cheese, Greek yoghurt, sweetener, vanilla, cornflour and eggs, using a wooden spoon or balloon whisk.
Pour the mixture onto the biscuit base. Add the raspberry mixture to a small sandwich bag and cut the corner off the bag. Pipe vertical lines across the surface of the cheesecake. Using a skewer, or the tip of a knife, drag across the cheesecake in alternating directions to create a pattern on the surface of the cheesecake.
Place on a low shelf in the oven and bake for 50-60 minutes, until set around the edges but still has a wobble in the centre.
Remove from the oven and leave to cool for 1 hour. Once cooled, place in the fridge to chill for a minimum of 2 hours.
Remove the cheesecake from the tin and cut into 16 squares. Serve with some extra raspberries or a swirl of aerosol cream, if you would like.