Preheat oven to 350 degrees. Grease and flour 13x9x2 baking pan.
In large saucepan, cook chocolate pudding as directed on package. Blend dry cake mix thoroughly into hot pudding, beating by hand or with mixer 1-2 minutes. Pour into baking pan.
Sprinkle batter with chocolate pieces and nuts. Bake 30-35 minutes or until wooden pick inserted in center comes out clean.
Serve warm or cool. Tastes like a rich brownie!