Line a 24cm square cake tin with baking paper.

Melt the chocolate, butter and syrup in a saucepan over low heat, whisking until smooth. Set aside ½ cup of the chocolate mixture. Use a rolling pin to crush the Marie biscuits (you should have a mixture of bigger pieces and crumbs) and stir into the chocolate mixture with the mini marshmallows until everything is coated with chocolate.

Tip the mixture into the prepared cake tin. Pour the reserved chocolate mixture over the top and smooth with a spatula.

Refrigerate the mixture for at least 2 hours, preferably overnight. Cut into squares or bars, dust with icing sugar and serve.

Tips: To make a grown-up version of this recipe, replace the Marie biscuits and mini marshmallows with 200g blanched hazelnuts (toasted and roughly chopped), 50g candied citrus peel and 80g chopped ginger preserve.

Also delicious with glace cherries, chopped Turkish Delight, ginger biscuits or chopped brazil nuts.

Pack rocky road squares into a tin, wrap with Petersham ribbon and give to a friend as a delicious gift.