Heat 1 tablespoon oil in a frying pan until hot. Cook chicken until brown all over. Set aside.
Using the same pan, heat the remaining oil and add the wine, if using, add the leeks and cook and stir until the leeks are tender and the wine has evaporated. Set aside.
Melt butter in a large pot. Stir in the flour to create a smooth paste. Gradually add the milk, stirring continuously until sauce thickens.
Add chicken and leeks to the pot and crumble in the stock cube and season. Cover and simmer over low heat for 10 to 15 minutes.
Meanwhile, line a 23cm x 30cm or similar size tin with puff pastry. Fill with chicken and leek mixture and cover with a layer of puff pastry. (At this stage, you can brush the top with egg, if desired).
Bake in a preheated 200 C / Gas 6 oven for 15 to 20 minutes or until pastry is puffy and golden. Remove from the oven and serve.
I only put puff pastry on the top of the pie!In the past when i've made pies and put pastry on the bottom,i find that pastry goes a bit soggy and i'm not keen on that!I left out the wine too,and after tasting the pie i don't think it needed it anyway! - 31 Jul 2011