Chop the Mars bars into small pieces and put them in a saucepan with the chocolate, butter and golden syrup.

Melt slowly over a low heat. Beat continuously whilst melting and beat well once everything has melted until the mixture is smooth.

Leave to cool slightly (approx 1 minute). Don't leave to cool for any longer than this, as the mixture will harden quickly.

In a large bowl, combine the melted mixture with the biscuits, Maltesers and marshmallows.

Transfer to a baking tin lined with non-stick parchment paper. Spread out evenly with a spatula and press down.

Allow to set for at least 4 hours in the fridge.

Remove from the fridge and cut into squares.

Optional: Drizzle with melted chocolate or dust with icing sugar.

Enjoy!