Line an 8x8 baking pan with parchment paper and set it aside.
In a medium saucepan, melt dark chocolate, butter, and golden syrup over low heat, stirring often. Remove from heat once nearly melted and let residual heat finish the job.
Place ginger cookies in a freezer bag and crush them with a rolling pin, leaving some large chunks.
Stir the crushed cookies into the warm chocolate mixture, then add mini marshmallows, dried cranberries, chopped pistachios, and orange zest. Mix everything well.
Pour the mixture into the lined pan, then chill in the fridge.
Melt white chocolate in a small heatproof bowl over simmering water, then melt the dark chocolate the same way.
Spread the melted white chocolate over the chilled rocky road, drizzle with dark chocolate, and use a toothpick to swirl for a marbled effect.
Sprinkle extra cranberries and pistachios on top, chill for at least 4 hours, then cut into squares and enjoy!