Pre-heat oven then fry the leeks and brussel sprouts until softened. Add the mushrooms, nutmeg and thyme and allow the mushrooms to soften. Stir in the potatoes, followed by the lentils and chestnuts. Cook the mixture for 2 minutes then add the double cream. Take off the heat and stir in the cranberry jam. Roll out the pastry and line each pie dish with the pastry (we suggest 12cm pie dishes), then add filling to each pie dish until full. Using the remaining pastry – cut out a pastry lid and place this on the top of each pie. Cut the top of the pastry lid and wash each pie with the beaten egg to glaze.