Preheat the oven to 350. Grease and flour two 10inch round cake pans.
For the cake, in a mixing bowl, cream the shortening and granulated sugar until fluffy. Add the eggs one at a time, mixing well after each. Sift flour with the baking powder,soda,salt and spices. Add the flour mixture alternately with the buttermilk,beginning and ending with the flour. Stir in the nuts and raisins, then stir in the jam.
Pour the batter into the prepared pans and bake for 30 to 40 minutes or until the cake pulls away from the pan. Cool the cakes in the pans for 10 minutes, then turn them out onto cake racks to cool completely.
While cake cools, make the icing. Melt the butter into a saucepan, add the brown sugar, and bring to a boil. Boil over low heat for 2 minutes, stirring constantly. Add the milk and continue stirring until the mixture returns to a boil. Remove the pan from the heat and scrape the mixture into a mixing bowl. Let cool. Add the confectioner's sugar a little at a time, beating well after each addition, until the icing is thick enough to spread. Fill and ice the cake.
Variation: You may prefer to bake this cake in a tube pan. Pour the batter into a greased and floured pan and bake for 15 minutes, then reduce the heat to 300 and bake for about 1 hour and 15 minutes or until the cake tests done. Cool as directed for the 10 inch layers.