Preheat oven to 350. Lightly grease a shallow baking dish large enough to hold mushroom caps in single layer. Remove stalks from mushrooms and set aside. Place mushrooms in dish and dot each with a dot of butter then season with salt and pepper. Cover dish with foil and bake 20 minutes. Place remaining butter in frying pan together with the garlic and heat until sizzling. Reduce heat and add parsley and chopped mushroom stalks and sauté for 5 minutes. Season with salt and pepper. Drizzle butter sauce over mushrooms and sprinkle with remaining parsley.