Peel and trim the carrot and leek and place the trimmings and peel in the large saucepan.

Coarsely chop the mixed mushrooms.

Assemble the food processor bowl with the slicing disc.

Pre heat the oven to 180°C.

Add Ingredients 1 (chicken, water, bay leaf, peppercorns, cloves) into the large saucepan with the trimmings.

Bring to the boil.

Reduce the heat and simmer for 1 hour.

Remove the chicken from the pot and set aside to cool.

Strain the liquid and reserve 1000 g of the liquid.

Add the first two of Ingredients 2 (flour, butter) into the food processor bowl.

Attach the lid and ensure it is locked into place.

Pulse until the butter is distributed through the flour.

Add the rest of Ingredients 2 (yolks, water) into the bowl.

Continue to pulse until the mixture comes together.

Form the pastry into a ball and wrap in plastic wrap.

Chill for 30 minutes.

Clean the food processor bowl and fit the Slicing Disc.

Slice Ingredients 3 (carrot, leek, celery) into the bowl.

Reserve the vegetables.

Add Ingredients 4 (oil) into the medium saucepan.

Heat over a medium heat.

Add Ingredients 5 (mushrooms) to the saucepan.

Cook until the mushrooms have reduced in volume and coloured.

Place the mushrooms into a large bowl.

Add Ingredients 6 (butter) to the medium saucepan.

Heat over a medium heat until just melted.

Add the cut vegetables to the pan.

Cook the vegetables, stirring regularly until the leeks and celery soften.

Add Ingredients 7 (flour) into the pan.

Stir in the flour and cook for 2 minutes.

Carefully pour in the reserved chicken stock.

Bring to the boil and cook until the liquid thickens.

Add Ingredients 8 (crème fraiche, mustard, seasoning) into the pan.

Stir until combined.

Add the sauce to the mushrooms and stir through.

When the chicken is cool enough to touch, tear the meat into bitesize chunks and add into the sauce.

Stir through and transfer the filling into the baking dish.

Place the pastry onto a lightly floured surface.

Roll out to around 4 mm thick.

Lay the pastry on top of the baking dish and trim any excess pastry that over hangs the edge.

Brush with Ingredients 9 (egg).

Bake for 45 minutes at 180°C until golden.

Serve.