Cream together butter and sugar until light and fluffy. Add eggs one at a time beating well after each addition. Stir in prunes. Combine flour, baking soda, salt and spices and add alternately with buttermilk to creamed mixture. Stir in walnuts. Pour into greased and floured 9-inch square pan. Bake in 350 degree oven 40 to 45 minutes or until cake tests done. Cool on rack. Cut into 9 squares. Serve with a dollop of sour cream or whipped cream. Top with brown sugar. Reprinted with permission from _Just Cakes_ From the C and H Sugar Kitchen Electronic format by Karen Mintzias