Preheat oven to 220 C / Gas 6. Grease a round 23cm loose-bottomed tart tin.
For the pastry:
In a bowl sift together the plain flour and salt. Rub in butter until mixture resembles breadcrumbs. Add cold water, a tablespoon at a time, and knead into pastry dough. Wrap in cling film and chill in the fridge for 30 minutes.
Lightly dust a surface with flour, roll out the pastry in a circle and line the bottom and the sides of the prepared tin. Remove any excess pastry and reserve.
Prick the pastry with a fork, cover with foil and place a layer of dried beans, rice or lentils on top. Bake blind for 10 minutes in the preheated oven. Remove foil and beans and bake for another 5 minutes, until light golden brown. Take out of the oven and set aside.
Reduce oven temperature to 180 C / Gas 4.
For the filling:
In a saucepan combine pumpkin purée, brown sugar, water, cassava flour, spices and salt and cook over low heat until the mixture thickens and the cassava flour dissolves.
Pour pumpkin mixture into the prebaked pastry case. Roll out reserved pastry and cut into desired shapes for decoration. Place on top of the filling and brush with milk.
Bake for 30 to 40 minutes until the filling has set and the pastry is golden brown.
Before serving let the pie cool completely.
Pumpkin purée can be found online or in speciality shops. You can also make your own.
Tapioca flour is a gluten free flour used widely as a thickener. Doves Farm is a well known brand. It is also referred to as tapioca starch or cassava flour.