For the coffee caramel,combine the caster sugar and ¼ cup water in a saucepan,bring to a boil,then simmer until the sugar forms a dark caramel. Stir in the brown sugar,espresso and 150ml cream and simmer for just a minute,stirring constantly until the caramel is dissolved. Set aside to cool to room temperature,then place in the fridge to thicken.

Combine 450ml cream,mascarpone and sugar in a bowl and whip to soft peaks. The mixture should not be too stiff. Place the coffee and brandy (or rum) in a deep tray and dip half the savoiardi biscuits into this coffee mixture until softened but not falling apart. Arrange these biscuits in the base of a 24cm square serving dish. Cover with a thick layer of the cream mixture,ensuring there are no air pockets. Repeat with another layer of soaked biscuits,laying the biscuits in the same direction as the first layer,and a final thick layer of cream. Tap the dish against the bench to flatten the top and remove any air pockets.

Add a few dollops of the coffee caramel to the top of the dish. Then,using a skewer,swirl the caramel into the cream mixture to create a pattern. Refrigerate for at least 3 hours before serving. Serve with the remaining coffee caramel.