Wash the potatoes very carefully, dry them. Poke them in several places with a toothpick and cook them subsequently in a microwave for 7-8 min. each. Wrap them in aluminum foil to keep them warm while you prepare the stuffing.
Cut the potatoes in 2 and remove some of the insides with a spoon. Mix that with the mushrooms, cheese and finely chopped parsley, stir well and fill the potatoes. If desired, crisp 10 min. on the grill or serve immediately.