Prepare chocolate fudge pudding as directed on the package. Blend cake mix (dry) into hot pudding; mix well. Pour into prepared oblong pan, 9x1 3x2". Sprinkle with 1/2 cup semi-sweet chocolate pieces. Sprinkle nuts on top. Bake 30 to 35 minutes at 350°. Serve warm with whipped cream, ice cream or plain.