Melt 20 grams butter in a large frying pan over medium heat; add kumara and leek. Cook, stirring occasionally, until tender. Transfer to a large bowl

Using the same pan, add chicken and garlic. Cook chicken 3-4 minutes each side, until browned and almost cooked. Add to kumara mixture.

In a separate smaller pan, melt remaining butter. Add flour; cook, stirring, until the mixture bubbles. Gradually stir in the stock. Bring to the boil; simmer, stirring, until thickened. Stir in cream and chives.

Add sauce to chicken mixture. Spread into a greased, shallow 23cm-square ovenproof dish with a rim. Stand separated pastry sheets on kitchen bench 5 minutes, or until partially thawed. Preheat the oven to 200°C (180°C fan-forced).

Cut three 1cm strips from one sheet of pastry. Brush the rim of the dish with a little water; press pastry strips onto rim of dish, join strips with a little water. Top pie with second pastry sheet, pressing firmly to seal pastry together. Trim edge.

Brush pastry with egg, place dish on an oven tray. Bake 30 minutes, or until browned.