For the cucumber moussaka, rinse the porcini mushrooms in cold water and soak in lukewarm water.
Peel, halve and stone the cucumbers, cut into slices and put aside.
Peel and finely dice the onions and fry them with the minced meat in oil.
Clean and chop the mushrooms and add to the mince with the porcini and the soaking water.
Cook until almost all the liquid has evaporated. Season heartily with pepper and salt, pour into a gratin dish (3 l capacity). Spread cucumbers on top.
Mix yogurt and eggs, add chopped dill and pour over cucumbers. Top with slices of cheese.
Bake the cucumber moussaka in the oven on the middle shelf at 200° Celsius (gas: 3) for half an hour.