For the fig tart pastry
To prepare the fig tart recipe combine the flour, baking powder, xanthan gum, salt, and butter in a food processor.
Pulse until the mixture resembles rough breadcrumbs.
Add the egg and 2-3 tbsp water, and pulse until a dough comes together around the blade; add more water if needed, pulsing to bring it together.
Turn out the pastry, knead briefly, and then pat down and shape into a disc.
Wrap with clingfilm and chill for 30 minutes.
For the fig tart filling
In the meantime, melt the butter in a large saucepan set over a medium heat.
Add the figs, apple, sugar, and cinnamon stick, and cook for about 10 minutes until soft and jammy.
Remove from the heat and stir in the calvados. Set aside to cool.
After the pastry has chilled, preheat the oven to 180°C (160° fan).
Roll out the pastry on a lightly floured surface to 0.5 cm thickness.
Cut out four even rounds and lift them into four individual baking ramekins or dishes, letting the pastry overhang their edges by about 3 cm.
Prick the bases with a fork and then fill with the fig mixture; make sure to discard the cinnamon stick.
Bring the overhanging edges of the pastry back over the filling and brush with the beaten egg wash.
Bake for 35-45 minutes until the pastry is golden-brown and cooked through.
Remove from the oven and transfer to wire racks to cool.
Once cool enough, dust the tops of the fig tarts with icing sugar before serving.