Preheat the oven to 200ºC, fan 180ºC, gas mark 6. In a mixing bowl, combine the flour, icing sugar, xanthan gum if using, and orange zest.
Using your fingers, rub in the freefrom spread until the mixture forms a dough. Place in the freezer for 20 minutes until firm but still pliable.
Cut out 20 discs of baking paper, slightly larger than an 8cm cutter.
Shape 20g of the pastry into a ball and place in the centre of a paper disc, then place another paper disc on top. Using a rolling pin, roll out the pastry ball to fit the paper discs.
Remove the top disc of parchment and stamp out a round using the cutter, removing any excess pastry. Keeping the pastry base on its parchment (which will remain underneath during cooking), press gently into a tartlet tin with your fingertips.
Repeat to make 10 mince pie bases. Return the remaining pastry to the freezer. Place a spoonful of mincemeat in each mince pie.
To make the lids, roll out the chilled pastry between 2 sheets of baking parchment (as in step 3). Peel off the top sheet, then use a cutter to cut out 10 lids, and place one on each mince pie.
Bake in the oven for 25 minutes, until firm and pale golden. Remove from the tin, slip off the parchment and place on a serving plate. Dust with icing sugar and serve warm.
Cook's tip: As the flour does not contain gluten, this pastry is quite tricky to work with. A pinch of xanthan gum makes the pastry easier to work with, but too much will make the pastry tough.
* Allergen information: Customers are advised to check allergen warnings on products at the time of purchase as allergen information on products is subject to change after publication of this recipe.