
Fry the onion for 3-4 minutes in well-heated oil, sprinkled with sea salt, until golden brown.

Mix the mushrooms with the onion and fry for 3-5 minutes. Add the flour, cream, nutmeg, salt and pepper. Mix everything and, reducing the heat to a minimum, simmer for 5 minutes.

Add the grated mozzarella, remove the pan from the heat and leave the dish covered for a few minutes to melt the cheese.