• Chop the remaining onion and slice the mushrooms. Cook the vegetables in the butter for a few minutes.
• Dice the chicken meat. Mix together the filling ingredients with 150 ml (1/4 pint) of the reserved stock and season to taste. Pour into an oval pie dish.
• Roll out the pastry to 5 mm (1/4 in) thick. Dampen the rim of the pie dish and cover with a strip of pastry.
• Brush the strip with water and cover with the remaining pastry to make a lid. Press the edges together, knock up and flute.
• Brush with beaten egg and decorate with any pastry trimmings made into leaves. Glaze the decorations and bake in a moderately hot oven for 35 - 40 minutes. Serve with courgettes or a vegetable of your choice.

Cook's Tip

• Knock up the edges of pies to seal the join. Press the edge of the pastry outwards with the side of your index finger, while knocking it inwards with the blunt edge of a round-bladed knife at a slight angle.