225g Hobnobs, broken up (you can use any kind of biscuit/cookie)
Icing sugar to decorate, optional
Line a baking tray with parchment paper.
Gently heat the butter, chocolate, golden syrup, and sugar in a pan, until the sugar crystals disappear. Stir in the cocoa powder and mix until smooth. Leave to cool for 15 minutes.
Put the Maltesers, chocolate chips, marshmallows, and Hobnob pieces in a large bowl. Once the chocolate has cooled, pour into the bowl and mix everything together.
Pour into the prepared baking tray and spread evenly. Place in the fridge for at least 2 hours. Turn out onto a board, sieve a little icing sugar over the top, then cut into small pieces. Keep in the fridge.