Quarter the mushrooms, only halve the smaller ones. Cut the bacon into strips or cubes. Finely chop the onions, garlic and parsley. Brown the bacon in hot fat and add the onion and garlic. Sweat briefly and add the mushrooms and wait for the mushrooms to take on a little color. Add the cream and water over medium heat and bring to the boil until the sauce starts to get creamy. Add mustard and parsley, season with pepper.
To get more sauce, I add some pasta water at the end.