Pre-heat the oven to 200°C/fan 180°C/gas mark 6.
Place the ProZero, water, psyllium husk, yeast and vanilla essence in a bowl and allow to stand for 5 minutes until the mixture thickens.
In a separate bowl, place the butter and sugar and rub together with your fingertips until you get a sand-like texture.
Add in the Fate All-Purpose Low Protein Mix and mix until combined.
Add the liquid mixture into the bowl and mix to form a sticky dough.
Place the dough out onto a clean, lightly dusted surface, knead for 1 minute and allow to rest for 20 minutes.
To assemble, mix together the light muscovado sugar and cinnamon in a bowl.
Divide the dough into 5cm balls.
Roll each ball in the melted butter and then the sugar and cinnamon mixture.
Place 4 tbsp of the sugar and cinnamon mixture into the bottom of a greased baking tin.
Place the metal cookie cutter on the middle of the baking tin and add the balls to the baking tin around it.
Spoon the remaining butter on top.
Bake in the oven for 35-40 minutes or until golden brown.
Leave to cool fully on a wire rack.
Drizzle with icing.
Serve with a bowl of icing to dip.
Add 100g Vitabite, chopped into small chunks, to the dough mixture for a chocolate flavoured twist.
Fate low protein all-purpose mix and ProZero are foods for special medical purposes and must be used under medical supervision.