Clean the mushrooms and cut them into slices. Clean the potatoes, kohlrabi and carrots. Cut everything into slices and pre-cook in boiling water for 5 - 10 minutes.
Grease a baking dish. Put all the vegetables in and season with salt, pepper and nutmeg. Whisk the cream with the egg and pour over the vegetables.
Put everything in the oven for 30 minutes at 180 ° C. Sprinkle the cheese on top 10 minutes before the end of the cooking time. Goes well with fish fillet or pork fillet.