For the potato-mushroom casserole, boil the potatoes, peel and slice them. Clean the mushrooms and cut them into slices, cut the young onions into fine rings.
Heat the oil in a pan and fry the mushrooms in it. Add the onions and bacon and fry briefly. Butter the casserole dish and place the potato slices on top.
Spread the mushrooms on top and then put the potato slices on top again and sprinkle the finely chopped chives on top.
Season the whipped cream with nutmeg, salt and pepper and pour over the mixture. Finally, sprinkle with cheese and bake in a preheated oven at 180 degrees for 20 minutes.
The potato-mushroom casserole can also be prepared without bacon. However, the bacon gives the casserole a tasty seasoning.