Boil the potatoes in their skins in salted water for about 20-25 minutes. Peel a squash, grate it and slice it.
Put baking paper in a tray and place a layer of potatoes.
Crush the telemeau with a gunpowder, put it in a bowl, add sour cream, finely chopped onion, add salt and pepper and mix well.
Add over the potato layer the cream cheese composition, put the drained mushrooms on top and put the last layer of potatoes.
Sprinkle with salt, pepper and a little ginger.
Grate the cheese and put on top, along with some mushrooms.
Bake for 30 minutes until lightly browned on top.