Combine the corn flour, flour, vanilla and salt together, add some of the milk to make a paste. Use a medium sized bowl. Beat the eggs into the paste and keep aside
Heat the rest of the milk till almost boiling – then stir it into the corn flour paste while whisking all the time. Pour it back into the saucepan (you can pour it through a sieve if you see any lumps at this stage) and bring to a gently boil whilst stirring all the time, until it is thick and bubbling.
Remove from the heat, mix in the butter and the caramel
Spoon the warm custard into a clean bowl, cover the surface of the custard with clingfilm (this will prevent a skin from forming) and leave to cool at room temperature.
Layer the caramel custard, chocolate cake (drizzle the cake layers with the vanilla liqueur), caramel, chocolate flake and whipped cream.
Make at least two or three layers
Finish off with whipped cream and garnish extravagantly.
The caramel custard can be made the day before and left outside in a cool place (not fridge).