Add the nuts in the food processor / chopper and blitz them until they are chopped into small but still distinguishable bits. Consider leaving a bit of crunch to the end result.
Remove the nuts, add the prunes to the food processor / chopper and blitz them until a composition like a paste is obtained. You should not overdo it, leave it a bit chunky.
Add the chopped nuts, the prunes paste, the cocoa and the cinnamon powder to a bowl and mix them with your hand. The heat from your hand will make it easier to handle.
Next, transfer the obtained composition to a small rectangular container, previously lined with baking paper. This will help removing the bars from the container, while also keeping it clean.
Press down the paste with an offset spatula and even the surface.
Remove the paste from the container with the baking paper. Tuck in and tightly secure the paste while wrapping it inside the baking paper, just like you would with a book that you are wrapping in a festive glossy paper :D
Put into the fridge overnight.
Take out from the fridge, cut in 6 and there you are :D You can set them on a plate and cover the plate with cling film, or wrap each bar individually in baking paper so you have more flexibility with carrying it around before eating it.
Enjoy!