Add the leeks and fry for 10 minutes, stirring often.

Stir in the cooked ham and turkey.

Pour in the cream and stock. Stir.

Add the mustard, tarragon and a good pinch of freshly ground black pepper.

Bring to a simmer. Reduce the temperature if necessary.

Simmer for 20 minutes, stirring occasionally.

Preheat the oven to 180 degrees C (fan-assisted).

Grease an ovenproof tin or pie dish.

Roll out the pastry into two pieces on a lightly floured surface. One big enough to fill the bottom and sides of the tin with a little hanging over it. The other big enough to comfortably cover the top.

Place the larger pastry piece into the tin and press into the bottom and sides, leaving a little hanging over the edges.

Spoon in the pie filling.

Cover with the other piece of pastry.

Press the edges together by firmly pinching around the tin.

Trim away any excess.

Whisk the egg in a small bowl.

Use a pastry brush to brush liberally on the top of the pie.

Use a knife to stab two holes into the middle of the pastry.

Place into the preheated oven and cook for 30 minutes until golden brown.

Remove from the oven and rest for a few minutes before serving.