In a small bowl, combine cranberries and brandy if desired; set aside. Place the apples in a large saucepan and cover with water. Bring to a boil. Reduce heat; cover and simmer for 8-10 minutes or until tender. Drain, reserving 2-3 tablespoons cooking liquid.
Place the apples in a food processor; cover and process until smooth. Gradually add reserved cooking liquid until applesauce reaches desired consistency. Return all to the saucepan.
Add brown sugar and cranberries. Bring to a boil. Reduce heat. Stir in butter until melted. Serve warm or refrigerate until serving. Just before serving, stir in the walnuts.