In the meantime, wash the mushrooms and cut into approx. 5 mm thick slices. Drain the tuna and use a fork to cut into very small pieces.
Heat the cream (do not boil yet) and let the cream cheese and 100 g Emmentaler melt in it. Add the herbs, salt and milk and bring to the boil briefly.
It is best to use a tall glass pan for gratinating. The mushrooms, tuna, tortelloni and the sauce are layered in several layers and then sprinkled with the remaining Emmentaler. You are welcome to do several layers.
The casserole takes so long in the preheated oven at 200 degrees top / bottom heat until the cheese melts and is yellow-brown (approx. 15-20 minutes).
Also delicious when cold.
The number of servings refers to 4 very hungry eaters.