Crumble the cake or chop into pieces. Retain half for use in a moment.
Arrange four large glasses or bowls, and split the cake between the four bowls. Push the cake down until it is fairly even.
Dollop some caramel on top of the cake (keep around 1 tablespoon of caramel for later).
Whip the cream and then spread over each trifle.
Chop up the Mars Bars and sprinkle over (keep a little to decorate).
Repeat with the remaining ingredients. Finish off with the cream.
Add a touch of milk to the retained caramel and drizzle over the cream along with the rest of the chopped Mars.
Finish off with melted chocolate or sauce. Place in the fridge until ready to eat. Enjoy!