If you are using fresh chicken, cut the chicken into bite-sized pieces and place it in a bowl with the soy sauce, garlic and cornflour. Let it stand while you prepare the leeks and mushrooms.
900 grams Chicken breasts OR, 4 tbsp Soy sauce, 2 tbsp Cornflour, 1 tsp Garlic paste
If you are using leftover or rotisserie chicken, simply pull the meat off the carcass and place it in a bowl ready to add to the filling when you need it
Top and tail the leeks and slice them lengthwise, then slice them into semi-circles.
3 Large leeks
Wipe the mushrooms with a damp cloth to clean off any dirty bits, then slice them or cut them into quarters.
225 grams Mushrooms
If you are using fresh chicken, melt the butter in a frying pan and when it's hot, add the chicken pieces and stir fry until they turn golden brown. Remove the chicken from the pan and set aside. Skip this step if you are using leftover/rotisserie chicken.
Add more butter to the frying pan, then saute the leeks and mushrooms for a few minutes until the leeks are softened and the mushrooms have released all their moisture. If you are using leftover chicken, add the garlic with the leeks and mushrooms.
Stir occasionally. The mixture should be quite dry, and should have reduced in volume by about half.
Pour the chicken stock into the pan and stir in the Dijon mustard and cream and season with salt and black pepper to taste.
1 cup Chicken stock made with 1 stock cube in 1 cup boiling water, 1/2 cup Single cream, 1 tbsp Dijon mustard, 1 tsp Salt or to your own taste, 1/2 tsp ground black pepper or to your own taste
Add the chicken.
Mix the milk and cornflour and stir through.
Bring to the boil and allow to cook until the mixture has thickened.
Pour the mixture into a pie dish large enough to hold all the filling. It should fit into a dish about 10" x 7" rectangular, and 2" deep.
Unroll the puff pastry, and place it on top of the pie.
Crimp the pastry against the edges of the dish to seal, then prick the pastry with a fork to allow any steam to escape during baking.
Brush the top of the pastry lightly with a beaten egg, to encourage the pastry to brown.
Place the pie dish on a baking tray and then bake in the pre-heated oven for 20 minutes.
Remove from oven and serve hot with your choice of vegetables.