Preheat oven to 180°C.
Heat the oil in a pan and fry the chicken for 3 minutes until sealed and transfer to a plate.
Return the pan to the heat and fry the leeks and mushrooms for 3 - 4 minutes, or until tender.
Return the chicken to the pan and add the wine.
Cook over a moderate heat until the liquid has reduced by half.
In a separate pan melt the butter and whisk in the flour, cook for 1 minute, stirring continuously.
Add the hot stock, a little at a time, and whisk until a smooth sauce i s formed.
Reduce the heat and stir in the cream.
Add the reserved chicken and vegetable mixture and season with salt and pepper and set aside to cool.
Grease 6 ramekins or small ovenproof dishes, divide the chicken mixture among the ramekins and stand on a baking tray.
Roll out the pastry on a lightly floured surface and cut out rounds to form the tops of the pies.
Place a round on top of each ramekin and brush the pastry with egg wash.
Bake for 20 - 30 minutes, depending on size, until the pastry is puffed up and golden brown.