Break up the chocolate and melt in either a double boiler or non metalic bowl over bubbling water, making sure base does not touch water, or use the microwave.
In a food processor whizz up the nuts till they are like breadcrumbs.
Break up the banana and add to the nuts, whizz till you have a smooth paste.
Let the melted chocolate cool for a couple of minutes and them pour into the food processor and add the salt and vanilla extract.
Whizz till completely mixed into a smooth paste.
Scoop out into a small jar.
Store in the fridge and use within 5 days