Place the ProZero, butter and cornflour into a saucepan.
Place over gentle heat and stir well with a whisk or spoon until the mixture begins to simmer and thicken.
Take off the heat and allow to cool.
Pour into a tall plastic container and using an electric hand-held blender, blend for 30-40 seconds.
Leave to cool, cover and place in the fridge to chill for at least 3-4 hours until firmly set.
Once set, preheat the oven to 200°C/Fan 180°C /Gas mark 6.
Place the Fate Low Protein All-Purpose Mix into a mixing bowl and stir in the sugar.
Rub in the margarine with fingertips until the mixture resembles breadcrumbs. Then knead into a dough.
Dust the work surface with Fate Low Protein All-Purpose Mix and continue to knead the biscuit dough until smooth.
Roll out dough into a 24cm circle. Place dough into the tin and prick the surface lightly with a fork.
Bake for 25 minutes until firm and golden brown.
Remove from the oven and leave it to cool in the tin.
Meanwhile, using an electric hand-held blender, whisk the cheesecake filling for about 2 minutes until light and airy.
Add sugar and lemon juice and whisk for a further 2 minutes.
Place on top of the biscuit base in the cake tin and use a spoon to level the surface.
Place in the fridge for 3-4 hours, preferably overnight.
To turn out, run a knife around the edge of the cheesecake to loosen, then open the spring and lift out the cheesecake.
Serve with fresh permitted fruit.
Fate All Purpose Mix and ProZero are foods for special medical purposes and must only be used under medical supervision.