In a bowl, beat egg yolks. Add potatoes, Parmesan cheese, parsley, onion and garlic powder; mix well. Beat egg whites until stiff; fold into the potato mixture. Brush eight muffin cups or small ramekins generously with melted butter. Divide potato mixture into cups. Brush remaining butter over potatoes. Bake at 375° for 30-35 minutes or until lightly browned. Serve immediately.