Whizz all ingredients in the food processor until it resembles crumbs of equal size.
Empty mixture onto a sheet of baking paper or foil and roll up like a sausage. Refrigerate while you melt about 60g chocolate.
Pour the melted chocolate on to the top of the sausage shaped mixture and use a spoon to spread evenly - this is quite messy!
Then refrigerate again until the chocolate sets, this time leave it on the foil but don't roll the foil up.
Once it's set, you can cut it into slices.
Keeps in the fridge for about a week...unless you tell your family about it!