Lightly grease a large tin or square brownie pan with a little butter and line with baking paper.
In a large saucepan, slowly melt the butter, dark and milk chocolate and golden syrup. Stir occasionally until there are no lumps of chocolate and it is smooth and silky. Remove from the heat. Leave to cool. Set aside some melted chocolate for the toppings at the end.
Place the digestive biscuits in a freezer bag and bash with a rolling pin or just the side of your hand until they are all broken into a mixture of crumbs and small pieces of biscuit. Set aside.
Mix the crushed biscuit, pretzels and mini marshmallows into the melted chocolate mixture in the saucepan, until everything is completely covered.
Tip the mixture into the lined baking tin, and spread it out to the corners. Flatten the mixture as best as you can with a spatula.
For the toppings, spread the melted chocolate (that you set aside earlier) over the rocky road. Top with mini marshmallows, pretzels, marshmallow fluff and the gold stars, sprinkles and glitter.
Refrigerate for at least 2 hours or leave overnight.