Mushrooms are such a great appetizer. This one is a little different, than what I have seen. This is from Recipes from the Heart cookbook from The Pampered Chef. I have also tweaked, with an added ingredient.
Preheat oven to 400°F. Remove stems from mushroom caps; set aside. Place caps, stem-side up, on baking sheet.
Chop enough stems, to measure 1/2 cup. In a medium bowl, combine chopped stems, ham, bread crumbs, bell pepper, garlic, and dressing; mix well. Spoon filling into mushroom caps, gently pressing filling, into caps.
Bake 15 minutes, then, sprinkle with Parmesan cheese. Put back in oven, until mushrooms are tender, and cheese is golden brown. Makes 24-30 mushrooms.