Line an 8-inch square baking tin with parchment paper.
Crush the biscuits in a sealed zip lock bag with a rolling pin.
In a separate zip lock bag, do the same with the mini eggs. Put a few aside to decorate the top.
In a medium saucepan, melt 200g chocolate, 80g butter & the golden syrup over a very low heat, stirring constantly.
Add the mini marshmallows (save a handful to decorate the top), crushed biscuits, cranberries and mini eggs (apart from the handful put aside) to a mixing bowl.
Pour over the melted chocolate and mix well until everything is combined.
Pour the mixture into the lined baking tin and spread it evenly.
In the same saucepan, melt 100g chocolate and 40g butter over a low heat, stirring constantly.
Pour the melted chocolate over the top of the rocky road mixture, then decorate with the leftover marshmallows and mini eggs.
Refrigerate for at least 2 hours or until the mixture is set.
Once set, remove from the pan and cut into 12 squares.