Apple and white chocolate rocky road

Name: Apple and white chocolate rocky road
Ingredients: 200g/7oz white chocolate, roughly chopped (or use chocolate chips); 2 tbsp golden syrup; 130g/4½oz unsalted butter, plus extra for greasing; pinch of salt; ½ tsp ground cinnamon; 200g/7oz cinnamon biscuits (or digestives); 100g/3½oz white mini marshmallows (if you can only find big marshmallows, use scissors to chop them into small pieces); 100g/3½oz dried apples, chopped into small pieces; 50g/1¾oz raisins; 1 tbsp icing sugar, for dusting