Bake and cool cupcakes. Ice cupcakes smooth with white icing. Cut bottom 1/4 in. off marshmallow and insert into cupcake. Trim front of marshmallow on an angle. Insert head on lollipop stick through marshmallow. Ice marshmallow smooth. Use tip 9 to pipe teardrop shapes at hem of dress (smooth into dress with finger dipped in cornstarch). Use tip 9 to pipe arms. Insert wand into hand and use tip 2 and copper icing to pipe hands and fingers. Use tip 2 and brown icing to pipe dot eyes and outline mouth. Use tip 2 and copper icing to pipe dot nose and cheeks. Use tip 2 and white icing to pipe dots and zigzag designs on dress.