Why not cook this delicious seasonal pie dish - the mix of herbs, cream and mushrooms taste great with a touch of hot mustard. Heat the oil in a large frying pan and cook the prepared mushrooms and shallots, stirring over a high heat for 5 minutes until golden and cooked through. Add the sherry and wholegrain mustard and cook again for 1 minute. Remove from the heat and stir in the crème fraîche, Dijon, parsley and thyme and season well with freshly ground black pepper. Set aside to cool. Preheat the oven to Gas Mark 7, 220°C, fan 200°C. Roll out the pastry on a lightly floured surface and cut 4 circles, large enough to line a 4-hole Yorkshire pudding tin. Fill each with the mushroom mixture, then cut a further 4 circles for the lids, lightly brushing the rims with a little water to enable them to stick. Make a slit in the top of each lid using a sharp knife, then rough up the edges of the pies using a sharp knife - this makes sure the base and the lids stay together throughout cooking. Use the egg to glaze the pies and bake in the preheated oven for 20-25 minutes, until golden and well risen. Serve with seasonal vegetables.