Clean the mushrooms and cut them roughly. Also cut the Fontina AOC into cubes by removing the rind and set aside.
In a frying pan, sauté a chopped shallot with a little olive oil. Add the mushrooms and cook for a few minutes. Add the marjoram leaves and season with salt and pepper.
In a bowl, mix the eggs with fresh cream, then add the cooked mushrooms. Season with salt and pepper and set the mixture aside.
Spread the phyllo dough sheets in a 24/26 cm baking dish, oiling each layer with the help of a kitchen brush. Once the layers are finished, pour the egg and mushroom mixture and the cubes of Fontina AOC in the centre.
Bake in a preheated oven at 180° for 15 minutes and then at 160° for a further 15 minutes. Serve warm.