A day before making the dish, boil the potatoes whole in their skins until tender.
Rinse under cold water, and set aside to cool completely, then cover and refrigerate.
Stir together the crème fraîche, garlic, and parsley.
Season generously with salt and pepper.
Cover and refrigerate overnight.
About an hour before eating, heat the oven to 400°F/200°C.
Slice the potatoes into neat ¼-inch/5 mm rounds.
Roll one sheet of the pastry into an 11-inch/28 cm circle and lay it on a greased baking sheet.
Leaving a 1-inch/2.5 cm margin all around, cover with an overlapping layer of potato slices.
Season with salt and pepper.
Spread over a layer of the cream mixture.
Repeat the layering, tapering in a bit as you go, until all the potatoes and cream have been used and the end result looks like an upside-down double-crusted pie.
You should have about three layers each of potato and cream.
Roll the second pastry sheet into a 12-inch//30 cm circle and drape it over.
Line up the edges and roll the bottom pastry margin up over the top one to seal, scalloping as you go all the way around.
Brush the torte all over with the egg and decorate the surface with the tines of a fork, if you like.
Cut an opening about the size of a quarter in the top to let the steam escape during baking.
Bake 10 minutes.
Turn the oven down to 375°F/190°C and continue baking until hot through and the pastry well browned, about 25 minutes.
If the torte starts browning too much, lay a piece of foil loosely on top.
Remove from the oven and slice onto a large serving plate.
Cut into wedges and serve with green salad as a main course
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