Put the flour in a large bowl, cut the cold butter with two knives. Ensure that a granular mass is created. Beat an egg and add it to the dough. Add the salt and stir with a fork so much ice water that a dough ball is created that is coherent but not wet. Roll out the dough on a floured board into a round piece with which we can cover the molds. Beboter the molds, cover them with dough and put them in the refrigerator for half an hour.

Preheat the oven to 180ºC. Remove the dough from the refrigerator and prick it with a fork. Fill the form with baking paper and hard beans. Bake the bottom blind in the oven for 15 minutes. Then take it out and let it cool down.

Fry the mushrooms in the butter, dry them and put them on the dough bottom, alternating with pieces of gruyere cheese. Beat the remaining eggs well and add salt, pepper and the cream. Pour this mixture onto the dough covered with mushrooms and cheese and place the mold in a preheated oven at 170ºC. Bake for about 25 minutes. Allow the tarts to cool and serve hot.