Squeeze the juice from the orange, and then remove the white from the peel. Place the peel, nuts and raisins in a food processor, and grind coarsely. Add the orange juice to the nut mixture.
Cream the shortening and sugar together until light and fluffy. Beat the egg, and add it to the creamed mixture.
Sift together the flour, soda, baking powder, and spices. Add the flour mixture alternately with the buttermilk to the creamed mixture. Stir in 3/4 of the nut mixture, and reserve the rest for the icing.
Pour batter into a greased and floured 10 inch square pan. Bake at 350 degrees F (175 degrees C) for about 1 hour. Cool.
To Make Frosting: Blend the cream and vanilla with the confectioners' sugar in a small mixing bowl. Add the remaining nut mixture and the grated orange rind. Frost the cooled cake with this icing.