Line an 8x8x3-inch tin with baking paper. Leave a little hanging over each edge to make removal easy later on.
Melt the chocolate, butter and golden syrup together in a saucepan then set aside to cool for a minute or two.
Add the digestive biscuits to a large bowl then crush them into medium-sized chunks using your hands or the end of a rolling pin. Stir in the chopped Crunchies and mini marshmallows.
Pour the melted chocolate/butter mixture into the bowl. Mix it all together until all of the dry ingredients are evenly coated in chocolate.
Transfer the mixture to your lined tin and press it down firmly into place.
Refrigerate for 3 hours then cut into squares and enjoy!
Video
Notes
Store in an airtight container for up to 2 weeks. Rocky road bars are best kept in the fridge.