A good way to use up leftover roast chicken. Cut a leek into slices about a cm thick and soak in cold water for 10 minutes or so,
to remove any soil from between the layers. Drain. Fry a chopped onion and the leeks for 5 minutes or so, until starting to soften,
then add cut up leftover roast chicken. Sprinkle over a ½ Tbs plain flour and mix well, then add a cup of chicken stock.
Bring to a simmer until it starts to thicken slightly, adding a couple of handfuls of baby spinach leaves. When this starts to wilt,
tip everything into an oven-proof casserole dish and let cool for a while. When ready to cook, scrunch up some sheets of filo pastry
into balls and use these to cover the chicken. Brush all over with melted butter and bake in a 180°C oven for about 30 minutes,
until the pastry is cooked and golden brown. Served with baby carrots.