01 -
Heat the oil in a large frying pan over medium heat. Add the sliced leeks and cook until softened, about 5 minutes. Add the cubed chicken thighs and cook, stirring regularly, until browned on all sides.
02 -
Add the butter to the pan and allow it to melt. Stir in the flour to form a roux, cooking for 1 minute. Gradually pour in the chicken stock, stirring continuously to avoid lumps, followed by the double cream. Continue to cook, stirring, until the sauce thickens. Season with salt and freshly ground black pepper.
03 -
Transfer the chicken and leek filling into a suitable pie dish. Unroll the puff pastry and place it over the filling. Trim and crimp the pastry edges to seal. Using a sharp knife, make a small steam vent in the centre of the pastry.
04 -
Brush the surface of the pastry with the beaten egg. Bake in a preheated oven at 200°C (fan 180°C) for 25–30 minutes, or until the pastry is golden and well risen.