Melt the dark chocolate in one bowl set over a pan of simmering water and melt the white chocolate in another bowl the same way. Remove both chocolates from the heat.
Add the salted peanuts to the dark chocolate and stir to combine. Lay a sheet of grease proof paper out onto a baking sheet and spread the dark chocolate and peanut mixture out into an even layer.
Blob spoonfuls of the white chocolate around on top of the dark chocolate and then use the handle of your spoon to swirl the white chocolate around so that it looks a bit like bark.
Allow to cool and then put in the fridge for at least 1 hour. Then break into shards and devour!