How to cook
Peel the potatoes, cut them into round slices as if for gratin and put them to boil until almost done. Put a little vinegar and salt in the boiling water. Then drain the potatoes well. Crush the onions and fry them in a little preheated oil.
Continue in this manner until the supplies finish. Beat both creams with eggs, flour and a little salt. Pour this over the potatoes and put it to bake in a heated oven at 356°F (180 °C) until tender. Finally, the potato and cream are sprinkled with a little grated cheese and baked.
Preheat oil in a small pan and fry the chopped mushrooms. Once softened, add the flour and stir until they fry. Dilute with milk while stirring until you get the desired consistency. Season the béchamel sauce with mushrooms with salt and black pepper, and a little nutmeg if you wish.
Serve a portion of baked potato and cream, topped with the sauce.