How to cook
Thoroughly clean the mushrooms and remove their stems. Arrange the caps in a slightly greased tray and put them to roast in a heated 392°F (200 °C) oven until they fill up with some water. Then take them out, remove the water and cool.
Heat 2 1/3 tbsp (35 g) of butter and fry the flour in it. While stirring continuously, top up with the hot milk and mix until thickened. Season the sauce with salt, black pepper and nutmeg to taste. Separately, fry the finely chopped bacon and add the finely crushed mushroom stems and onions.
Optionally, add a little garlic to taste. Once braised, add the finished béchamel sauce and parsley. Remove from the heat and mix everything with the coarsely grated cheese. Fill the mushrooms with this filling, and if some remains you can pour it in the pan.
Put the mushrooms with cheese and bacon to cook in the oven to a nice red tan, at 392°F (200 °C).