Cream together sugar and butter or margarine. Beat in eggs. Stir together flour, and spices; add to creamed mixture alternately with butter/sour milk, beating til well blended after each addition. Fold in blackberry jam or preserves and nuts leaving swirls of jam. (DO NOT OVERMIX) Turn into greased and lightly floured 9 x 9 x 2-inch baking pan. Bake at 350 degree F. oven 25 minutes or until done. Cool completely. Frost with Carmel Icing. CARMEL ICING: In small saucepan, melt butter or margarine; stir in brown sugar. Cook stirring constantly, til mixture bubbles; remove from heat. Cool 5 minutes. Stir in milk and blend in powdered sugar; beat til spreading consistancy is reached.