Remove the stems from the mushrooms and use only their caps for stuffing. Arrange them in a greased baking tray.
Heat butter in a pan and fry the chopped garlic and finely chopped mushroom stems. After a little while, add the finely chopped chicken and salt to taste. Put nutmeg and black pepper in.
Remove the filling from the heat and mix it with the chopped parsley and cream cheese. Fill the mushrooms with the stuffing. On each mushroom cap, place a small square of processed cheese, sprinkle with pine nuts and add about a cup of warm water to the tray.
Put the stuffed mushrooms to bake in a moderate oven.