Debone the chicken, removing the skin and bones and shred chicken or cut into cubes.

In a high sided sauté pan or pot, melt the butter over medium heat and sauté the onions and celery until soft (this should take 15 minutes).

Add the garlic and sauté another minute to remove the raw taste.

Add the flour and cook out for at least 5 minutes on a medium heat.

Add the mushrooms and fry for another 3 minutes.

Slowly add the stock and stir continually to ensure there are no lumps and the mixture starts to bubble and thicken.

Let it simmer for about 10 minutes until the mushrooms are cooked.

Add the frozen corn, carrots and peas and allow to come to a boil while stirring all the time.

Add the creme fraiche, string continually and bring to the boil before adding the chicken.

Reduce the heat to low and stir continually while it simmers and thickens, about 10 minutes.

Adjust the seasoning and remove from the stove to cool.

Preheat the oven to 200 degrees celcius/ 180 celcius with fan / 400 F / Gas mark 6.

Roll out the pastry and line two 20 cm pie dishes ensuring that the pastry overlaps the sides a bit as it may shrink during baking if not rested enough. I chilled it again for another 10 minutes before baking.

Line the base with parchment paper and baking beans or beans, and bake blind for about 10 to 15 minutes.

Remove the parchment paper and beans and bake for another 5 minutes, then leave to cool.

Fill the cooled pastry case with the chicken filling and cover with the second sheet of puff pastry.

Trim the edges and make two slits at the top to allow steam to escape.

Brush with beaten egg then bake for 30-40 minutes or until the pastry is golden and cooked through.

If you find the pastry browning too much but it is still not completely cooked then cover the brown edges with foil for the remainder of the cooking time.