Directions :
Preheat oven to 400deg F.
Wash mushrooms and remove stems.
Set caps aside, and chop half of the stems.
Saute chopped mushroom stems,celery, onion and pepper in butter for 2 minutes.
Transfer to a plate and cool in refrigerator.
Combine sauteed vegetables and all other ingredients (except cheese slices) and mix well.
Place mushroom caps in a sprayed or buttered baking pan stem side up.
Spoon 1 tsp stuffing into each mushroom cap.
Cover with a piece of sliced cheese.
Bake for 12-15 minutes until cheese is lightly brown.
