Heat a large frying pan and sear the pigeon in a little rapeseed oil until the skin is evenly coloured. Remove from heat and remove the breasts from the pigeon. Once cooled put in the fridge until needed.
Heat a knob of butter in a large saucepan, add the spinach, wilt and season. Spread the cooked spinach out on a clean tea towel to cool, then squeeze the excess water out of the spinach in the tea towel.
Heat a knob of butter in a frying pan. Peel and finely chop the shallots, and place half the chopped shallots in the pan, cook without colouring for 1 minute, add half the wild mushrooms and the crushed clove of garlic. Turn up the heat and fry for 30 seconds, finish by adding a couple of drops of white truffle oil and half the chopped parsley and then season. Remove from heat.
Sear the duck liver in a frying pan and season. Remove from heat.
To make the pithivier, all your ingredients must be cold. Roll out the puff pastry to about 1cm thickness and cut out 4 discs using a side plate as a template, and 4 smaller discs using a saucer.
Lay the 4 smaller discs of pastry out, divide the spinach between them, top with two breasts of pigeon, the mushroom mix and the duck liver, leaving a 2cm gap around the edge. Brush with the egg and place the bigger disc on top of the liver, press the sides of the bigger disc and crimp the edges together. Take a knife and decorate the top of the pithivier by scoring the pastry, make a hole in the middle of the top for the steam to escape whilst cooking. Brush all over with egg yolk and then
Sautée the rest of the shallots in a pan with a little butter and add the rest of the mushrooms and parsley to finish.
To make the sauce, put the red wine, balsamic vinegar, shallot, thyme and mushrooms into a large saucepan, place on a high heat and reduce by three-quarters. Pour in the stock and continue to reduce until the sauce is a good pouring consistency.
Serve the pithivier with the hot sauce, sautéed mushrooms and shavings of fresh truffle (if using).