preheat oven to 350f. In a bowl, with your fingers, mix flour, oil, water, and salt until it forms homogeneous dough. Do not over mix. Divide dough into two equal balls, on a floured surface, roll out the first ball and place it in a ten inch pie plate, letting extra dough hang over sides. In a bowl , mix potatoes with onions, herbs, nutmeg, pepper, and salt. place potato slices in a cicular layer in the piecrust, making sure to have more slices in the middle.
roll out the second ball of dough and place it over the potatoe Crimp the two crusts together to seal the pie. With a knife, cut out a cross in the middle and fold back to create a chimney. Lightly beat the eggyolk with 2 tablespoons water. brush the top of the pie with the egg wash. Bake 45 to 50 minutes.
remove from oven. cut out a circle in the middle of the crust and pour cream inside, poking with a knife and tilting the pie to distribute the cream as best you can, replace the circle. serve hot warm or cold