To prepare the pastry
Place the puff pastry sheets on a lightly floured surface. Cut out a 20cm disc from the one sheet and a 23cm disc from the other. Place each on a baking sheet and refrigerate.
To make the filling
Fry the bacon in a little oil until crispy. Drain the porcini mushrooms (keep the soaking liquid), add them and the fresh mushrooms to the pan, and fry until tender. Deglaze the pan with the soaking liquid. Set aside to cool. Bring a large pan of salted water to the boil. Add the potato slices and boil for 3 minutes or until just tender. Drain and refresh under cool water. Pat the slices dry with kitchen towel and place in a large mixing bowl. Mix the creams together and pour half the mixture over the potatoes. Add the shallots, garlic, nutmeg and salt to the potatoes and mix gently.
To assemble the pie
Preheat the oven to 220°C. Place the smaller pastry disc on a baking sheet and arrange overlapping potato slices in layers, alternating with the bacon and mushroom mixture, but leaving 2cm around the edge. Beat one of the egg yolks with a little bit of water and brush the edge of the disc. Lay the second pastry disc over the top, pressing the edges together firmly and gently pressing trapped air from the filling. Pinch the edges between thumb and forefinger. Chill the pie for 20 minutes. Brush the top of the pie with the remaining egg wash and then, using a sharp knife, score the pastry lightly into portioned sections and score a 2.5cm wide circle in the centre to create a small lid. Bake in the centre of the oven for 20 to 25 minutes until puffed and golden, then reduce the heat to 180°C. Bake for another 10 minutes. Cover the pie with a loose sheet of foil if the pastry browns too quickly.
To make the sauce
Gently warm the remaining cream in a small pan. Remove from the heat and stir in the remaining egg yolks, the chopped parsley and a pinch of salt. Remove the pie from the oven and gently loosen the small pastry lid with the handle of a teaspoon. Slowly pour in the cream and egg mixture, tilting the baking tray slightly to allow the mixture to soak through the potato filling. Replace the pastry circle and return the pie to the oven, covering with the foil if the pie seems golden enough. Bake for a further 10 minutes. Remove from the oven and allow cooling for 5 minutes, then slice into wedges and serve.
Change with the season
To make a delicious winter version, prepare the pie exactly as above but substitute the potato with slices of butternut and sweet potato. Make a sage and brown butter sauce by caramelising 125ml butter in a saucepan until it smells nutty and turns light brown (but not burned). Add a handful of sage leaves to the hot butter until the leaves shrivel slightly and become crisp. Serve the butter with warm slices of the pie.
By Vickie de Beer