If you are using dried bilberries you will need to place them in a bowl and cover with water the day before you want to make the pie and leave to soak overnight.
Preheat the oven to 180C/350/gas 4.
Grease the pie dish with butter.
To make the pastry sift the flour and salt into a large mixing bowl or food processor bowl.
Add the butter and rub in (or process if using food processor) until the mixture resembles fine breadcrumbs.
Place the egg yolk in the cup and add the ice cold water and whisk together.
Add to the pastry mix and bring together to make a dough adding more water if the dough is too dry. If using a processor add the egg mixture and whizz until the mixture forms a ball of dough.
Wrap in clingfilm and place in the fridge for 30 minutes.
To make the filling place the bilberries and caster sugar in the medium mixing bowl. If using soaked dried bilberries, strain them before you place them in the bowl.
Stir thoroughly, cover with clingfilm and allow to macerate for half an hour.
Remove the pastry from the fridge and place on a lightly floured work surface.
Cut the pastry in half and roll out to fit the bottom of the pie dish.
Line the pie dish and trim any overhanging pastry.
Spoon the bilberry and sugar mixture into the pie and brush a little water onto the edges of the top of the pie base.
Roll out the remaining pastry and place over the top of the bilberries and seal the edges by crimping.
Cut any excess pastry off and use it to cut shapes out to decorate the top of the pie, sticking them on with beaten egg.
Make a hole in the middle of the pie top to allow the steam to escape.
Brush with the beaten egg, sprinkle with caster sugar and bake for 45 to 50 minutes or until the pastry is golden brown and the filling is bubbling. If the pie looks as if it is getting too brown (it should be golden) then place a piece of kitchen foil over the top.
Remove from the oven and serve immediately with cream.
