Add the flour and butter into the pan and cook, stirring, for 1
min.
With the pan on a medium heat, gradually stir or whisk in the
stock, followed by the cream, then add the diced veal.
Bring to the simmer, season with salt and ground white pepper
and cook for 1 hour.
In a separate pan soften the onion in 10 g of butter, and then
add the leek and finally the mushrooms cooking until tender without
any colour.
Add this mix and the diced ham to the veal pan and continue to
cook for 30 more minutes until the meat is tender.
Remove from heat and chill adding the tarragon when cool.
Spoon the filling into a large pie or baking dish (approx. 20 x
30cm) with a lip, this can be done the previous day or in the
morning ready to finish.
Heat oven to 2000°C/gas 7.
On a floured surface, roll the pastry to the thickness of 8
mm.
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, and 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.
Serve with boiled new potatoes and seasonal greens.