Preheat oven to temperature specified on the German chocolate cake mix box.

Prepare cake batter as directed on box.

Bake cake as directed on box.

Let the cake cool completely.

Cut the cooled cake into bite-sized pieces.

Prepare chocolate pudding according to package directions.

Cut Reese's peanut butter cups into small pieces.

In a large punch bowl or trifle dish, create the first layer by placing some cake pieces.

Spoon a layer of prepared chocolate pudding over the cake pieces.

Sprinkle a layer of chopped peanut butter cups over the pudding.

Spread a layer of Cool Whip over the peanut butter cups.

Repeat layers in the same order: cake, pudding, peanut butter cups, Cool Whip.

Continue layering until all ingredients are used, finishing with a layer of Cool Whip on top.

Refrigerate for at least 30 minutes before serving to allow flavors to meld.