it's not a cake at all
it alternates layers of graham crackers, pudding/whipped cream, and chocolate
here's the one my mom made growing up:
Line a 9x9 pan with graham crackers. Prepare 1 pkg. instant vanilla pudding, using 1 ½ cups cold milk. Fold 1 cup coolwhip into pudding. Pour ½ over graham crackers then put another layer of graham crackers, pudding then graham crackers.
Frosting: melt 3 Tbsp. butter, stir in 2 T. cocoa. Add 1 ½ cups powdered sugar – makes crumbs. Beat in 1 egg. Mixture should be pourable like a glaze (not runny). If runny, add more sugar. Pour over frosting.
Chill.