To make the pastry, rub the Fate Low Protein All-Purpose Mix and the margarine together in a mixing bowl until it resembles coarse breadcrumbs.
In a separate bowl, add the sugar to the water and stir until combined.
Add the wet mixture to the dry mixture and stir until combined.
Leave the pastry dough to rest for 10 minutes.
Dust a clean work surface with Fate Low Protein All-Purpose Mix and knead the pastry for a minute on the work surface until smooth.
Divide the pastry into two balls.
Roll 1 ball of pastry out with a rolling pin and place in the baking tin, pressing the pastry into the sides of the tin.
To make the filling, heat the cherries, sugar, water and corn flour in a pan over a medium heat until it reaches a thick consistency.
Roll the remaining pastry to a rectangle that will cover the baking tin. Cut into 8 long strips about 2cm wide. Weave the strips under and over each other on a rimless baking sheet dusted with Fate Low Protein All-Purpose Mix to make a lattice large enough to cover the top of the pie. Place in the fridge to chill.
Preheat an oven to 200°C/180°C fan/gas mark 6.
Pour the cherry mixture into the pastry case. Brush pastry rim with Prozero, then slide the chilled lattice off its sheet and onto the pie. Press the edges down to seal.
Brush the lattice with ProZero and bake in the pre-heated oven for 30 mins or until golden.
Remove from the baking tin and cool on a wire rack.
Serve with ProZero whipping ‘cream’, ice ‘cream’ or custard.
Fate low protein all-purpose mix and ProZero are foods for special medical purposes and must be used under medical supervision.