Pack the chicken into a large saucepan and sprinkle the onion over the top, then add the cinnamon, ginger, turmeric and seasoning. Cover the chicken with the measured water. Cover and simmer for 1 hour until tender. Lift the chicken out of the stock and put on a plate to cool. Boil the stock rapidly for about 10 minutes until reduced to one-third.
Dice the chicken, discarding the skin and bones. Strain the stock into a jug. Discard the cinnamon stick, then add the herbs, raisins and almonds to the chicken. Whisk 200 ml (7 fl oz) stock with the eggs.
Brush a 23 cm (9 inch) springform tin with a little of the melted butter. Unroll the pastry, then place one of the sheets in the tin so that it half covers the base and drapes up over the side and hangs over the top of the tin. Add a second pastry sheet overlapping a little over the first and brush with a little melted butter. Continue adding pastry, brushing alternate sheets with melted butter until two-thirds of the pastry has been used and the tin is thickly covered.
Spoon in the chicken mixture, then cover with the eggs and stock. Arrange the remaining pastry over the top in a smooth layer, then fold in the sides in soft pleats, brushing layers of pastry with butter as you go. Brush the top layer with the remaining butter, then bake in a preheated oven, 180°C (350°F), Gas Mark 4, for 40–45 minutes until golden brown and the filling is set.
Leave to cool for 15 minutes, remove from the tin and transfer to a chopping board. Dust lightly with icing sugar and cinnamon and serve warm.