For the pastry: On a lightly floured work surface, roll out the puff pastry to a 1/2 cm thickness. Brush the rim and outside edge of the filled pie dish with beaten egg, then lay the pastry over the top of the dish. Press the edges of the pastry down to reach down the sides of the pie dish, then trim any excess. If desired, use any trimmings to decorate the top of the pie.
Brush the pastry all over with the remaining beaten egg, then cut a small cross in the centre of the pastry using a sharp knife to allow the steam to escape. Transfer the pie to the roasting oven and cook for 20 minutes, or until the pastry has risen and is golden-brown and the filling is piping hot.
For the filling:
Season the pieces of wild boar shoulder with salt and freshly ground black pepper.
Heat a large saucepan over the boiling plate. Add the olive oil, then fry the wild boar pieces for 3-4minutes, or until browned on all sides. Remove the browned wild boar from the saucepan and set aside in a warn dish.
Add the pancetta/bacon to the dish the wild boar was cooked in. Fry for 1-2 minutes, or until some of the fat is released from the meat.
Add the shallots, carrots and mushrooms and fry for 2-3 minutes, or until softened. Then add the bay leaves and parsley sprigs and return the boar pieces to the pan. Add the flour and stir well until it coats all of the ingredients.
Add the wine and scrape up any browned bits from the bottom of the pan. Bring the mixture to the boil. Simmer the mixture until the volume of liquid has reduced by a quarter, about 15-20 minutes.
Add the beef stock, then cover the casserole dish with a lid. Simmer gently for 2 hours, stirring occasionally, until the boar is very tender. Transfer the cooked pie filling to a pie dish and set aside for at least 30 minutes to allow the filling mixture to cool.