Clean mushrooms with damp paper towels. Remove mushroom stems; chop and set aside 1 cup stems. Dip mushroom caps in melted butter; place caps, top side down, in a shallow roasting pan.
Sauté reserved mushroom stems and crab meat in 1/4 cup butter in a large skillet until tender. Stir in breadcrumbs, parsley, salt, and pepper.
Spoon crab meat mixture into mushroom caps, and sprinkle with Parmesan cheese. Bake at 350° for 15 minutes. Transfer to a serving platter, and serve hot.