With an electric mixer whip the cream at high speed, until very thick. Using a rubber spatula gradually fold the dulce de leche into the whipping cream. Depending on the dulce de leche’s consistency, the mixture might not be completely uniform but this is fine.
Pour the milk in a plate and quickly soak few plain cookies/ crackers inside. Arrange them on the bottom of a rectangular serving plate or pan. Spread on top some of the frosting.
Soak some cocoa cookies/ crackers and arrange them on top of the frosting.
Continue the process until using all the cookies or crackers. Ideally the cake will have six layers (3 plain and 3 cocoa). Spread the remaining frosting on top and around the sides of the cake.
Wrap the cake in cling film and transfer it to the fridge for at least 6 hours or overnight.
Before serving decorate with cocoa powder and fresh fruits.