To make the pastry cream, mix the egg yolk and sugar in a bowl. Sift the cornstarch and ﬂour and add to the egg mixture to form a paste.
In a saucepan, heat the milk and vanilla beans to boiling, remove from the heat and add to the egg mixture. Stir together until blended.
Return the mixture to the saucepan and stir vigorously on a medium heat until thickened.
Remove and chill.
When cooled, whisk to loosen up the texture and fold in the whipped cream.
Cut the pound cake into chunks and grill for a few seconds until warm and toasted.
Heat sugar in a dry pan to make a dry caramel. When it starts to smoke, add the butter and then cream.
Remove from the heat and allow to come to room temperature.
To assemble, alternate between layers of the sliced banana, grilled banana pound cake, pastry cream and the caramel.