Cream butter and sugar; beat in egg. Drain syrup from oranges and save. Stir Mandarin oranges into sugar. Sift together the flour, soda and salt, then stir in raisins and nuts. Drop onto greased cookie sheet with a teaspoon. Bake in oven at 190ºC or 10 minutes. Blend enough orange syrup into 10x sugar to make a spreadable frosting. Frost and sprinkle orange rind over frosting.