Line a sheet pan with parchment paper.

Melt the dark chocolate in a heatproof bowl set over a pot of barely simmering water, stirring until completely smooth and glossy.

Pour the melted dark chocolate onto the lined pan and spread into an even layer about 1/4 inch thick with an offset spatula.

Melt the white chocolate the same way, then drizzle it over the dark layer in loose lines.

Swirl the two chocolates together lightly with a skewer to create a marbled pattern, without fully blending them.

Scatter the chopped gold coins, pistachios and cranberries over the top while still wet, pressing gently so they stick, then finish with a pinch of flaky salt.

Chill 1 hour, until the bark is firm enough to snap cleanly, then break into shards with your hands.