1. To make the base layer, blend nuts first to flour-like consistency - then add the rest of the base layer ingredients and blend until you have a bread crumb consistency. Compact really firmly into the base of the spring form tart dish tin ensuring an even spread.
2. To make the caramel layer, blend the ingredients for the caramel layer for 10 minutes until super smooth and caramel-like. Once blended if the mixture is too stiff, add a little more water. Spread a really even layer of caramel on top of the base layer doing your best to give a smooth top for the chocolate layer.
3. Finally, melt the dark chocolate in a bowl over a pan of simmering water and spread over the top to seal the tart. Chill until set.