Preheat oven to 350 degrees F (175 degrees C). Lightly grease a baking sheet.
Remove stems from mushrooms and chop fine. In a small bowl, mix together the chopped mushroom stems, bread crumbs, Parmesan cheese, parsley, garlic, olive oil, salt, and pepper.
Stuff the mushroom caps with the mixture. Place on the prepared baking sheet.
Bake for 15 minutes in the preheated oven, or until the mushrooms are tender and lightly browned.