Poach the chicken gently in the stock alongside any trim from
the celeriac and onions plus the bay leaf for approximately 30
Remove from the heat and cool to room temperature, then
carefully pick the meat away from the skin and bone.
Pass and reserve the poaching stock.
Heat the oil in a large, non-stick frying pan, sauté the
onions, celeriac, bacon and mushrooms until glazed and tender and
keep to one side
Add the flour and butter into the pan and cook, stirring, for 1
minute. With the pan on a medium heat, gradually stir or whisk in
the stock, followed by the cream, then add the picked chicken,
garnish and tarragon back to the pan.
Bring to the simmer, seasoning with salt and ground white
Spoon the filling into a large pie or baking dish (approx. 20 x
30cm) with a lip and leave to cool.
Heat oven to 200°C/gas 7.
On a floured surface, roll the pastry to the thickness of 8
Cut a long strip as wide as the rim of the pie dish and, using
a little of the egg, fix to the edge of the pie dish.
Brush with egg, then lift the rest of the pastry over the pie,
using the rolling pin to help. Gently press the edges with your
fingers and trim with a sharp knife.
Brush lightly with egg to glaze, then bake for 30 mins or until
the pastry is risen and dark golden brown.