Crumble the soft cake into small bite-sized pieces and set aside.
Place a layer of cake crumbs in the bottom of a serving dish.
Spoon banana pudding evenly over the cake layer.
Add a thin layer of buttercream frosting on top.
Spread whipped cream gently to create an airy layer.
Repeat the layering process with cake, pudding, and whipped cream until the dish is filled.
Spread a very thin layer of frosting or gently swirl it into the pudding layer to avoid compressing the soft cake.
Top with a final generous layer of whipped cream.
Sprinkle shaved chocolate evenly for garnish.
Cover and chill the dessert for at least 1 hour.
Serve chilled once the layers have softened into a creamy, spoonable texture.