Break up the chocolates and melt together
Add the butter and melt again, stirring until incorporated
Pour in the condensed milk and add a pinch of salt
Stir thoroughly until well combined
Roughly bash up the shortbread or pulse in a food processor until you have a mixture of crumbs and chunky bits
Add the shortbread mixture and raisins to the chocolate mix and stir well
Tip the mixture into a lined 28 x 20cm tin and press gently to the edges, leveling it off
Melt the chocolate for the topping together
Stir in the butter until incorporated
Pour the topping over the base and spread to the edges with a palette knife
Tap the tin on the work top to level it out
Sprinkle with a pinch of salt and decorate as desired
Leave to set in the fridge for at least a couple of hours
Cut into small squares and serve
