Start this recipe by melting the butter in a saucepan and mix in the cocoa powder and crushed biscuits. Press into the base and sides of a 9 inch fluted flan tin. Place in the fridge to firm for 10 minutes. Meanwhile, slightly heat the caramel in a microwave if not a soft spreadable consistency then spread all over the biscuit base. Cover the caramel with a layer of chocolate sponge and press down to stick. Next, make the caramel latte using your coffee machine but make it short. Use the latte caramel to soak the chocolate sponge using a pastry brush. Finally, melt the chocolate in a bain-marie or in the microwave and stir in the double cream, mixing to a ganache. Pour this mixture over the soaked sponge and even out. Sprinkle the top with sea salt and place in the fridge to set for 2-3 hours before serving dusted with cocoa powder.