Put the butter, caster sugar, flour and lime zest in the processor and pulse to a smooth paste. Scrape down sides between pulses
Press the shortbread mix into an oiled tin and prick with fork. Bake for 20 minutes and leave to cool.
For the filling, place the butter, sugar, golden syrup and condensed milk in saucepan over a low heat and stir until melted.
Turn up the heat and boil for 10 minutes until caramel is golden. Mash the banana with the orange essence until very soft and add to the caramel.
Pour the banana-caramel mix over the shortbread base and leave to set in the fridge.
Melt the chocolate in a bowl over a pan of simmering water and add the whole cardamom pods, star anise and cinnamon to infuse the chocolate with spice. Sieve the melted chocolate to remove any spice and spread on top of the cooled caramel.
Drizzle white chocolate over the top and cool. Top with freshly shaved coconut if you wish.