Line a 20cm x 30cm slice pan with baking paper, extending paper 3cm over the long edges.
Stir chocolates, butter and syrup in a small saucepan and heat oven low heat for 2 minutes or until chocolate and butter are melted and smooth. Transfer to a large bowl. Set aside for 10 minutes to cool.
Stir in violet crumble and peanuts until well coated. Place in prepared pan pressing slightly to compact. Sprinkle with salt. Refrigerate until firm and set (overnight if you can!)