Ingredients
For the filling
30g/1oz butter
1 onion, chopped
2 garlic cloves, chopped
500g/1lb 2oz Jerusalem artichokes, peeled and cut roughly into 1.5cm/½in thick chunks
1 orange, zest only
150ml/5fl oz dry white wine
2½ tbsp plain flour
300ml/10fl oz hot chicken stock
salt and freshly ground black pepper
700g/1lb 9oz boned chicken breasts and legs, cut into 3-4cm/1½in chunks
150ml/5fl oz double cream
For the pastry top
500g/1lb 2oz ready-made puff pastry
plain flour, for dusting
1 free-range egg, lightly beaten

Method
1. For the filling, heat the butter in a large heavy-bottomed lidded pan and gently fry the onion and garlic until softened but not coloured.
2. Add the Jerusalem artichokes, grated orange zest and white wine and boil down until the wine has virtually disappeared.
3. Sprinkle over the flour and stir for a few seconds so that it is evenly distributed. Gradually add the stock and stir to make a sauce. Season with salt and freshly ground black pepper, then add the chicken and stir well.
4. Cover and simmer for about ten minutes, stirring occasionally. Remove the lid and simmer uncovered for five minutes, until the sauce has thickened. Add the cream, stir and cook for a final 3-4 minutes. Adjust the seasoning, to taste.
5. Transfer the filling mixture to a 1-1.5 litre/1¾-2½ pint ovenproof pie dish and leave to cool slightly.
6. For the pastry top, roll the pastry out thinly on a floured surface. Cut out a couple of long strips about 1cm/½in wide. Brush the edge of the pie dish with the beaten egg. Lay the strips of pastry on the edge, curving to fit and cutting so that they go all the way around but don't overlap. Brush them with egg, then lay the remaining pastry sheet over the top. Trim off any excess and press the pastry down all around the edge to seal. Use the pastry trimmings to make leaves or flowers and glue them in place with the egg wash. Make a hole in the centre so that steam can escape, then chill the pie in the fridge for half an hour.
7. Preheat the oven to 220C/425F/Gas 7.
8. Brush the pastry top all over with egg wash and place in the oven. After 10-15 minutes, when the pastry is golden-brown, reduce the heat to 190C/375F/Gas 5. Continue baking for a further 20-25 minutes. Serve hot.