Melt the 2 chocolates in two different heatproof bowls set over a pan of simmering water or in the microwave.
Line two baking sheets with parchment paper. Pour the melted dark chocolate over the paper and spread with a spatula in one baking sheet.
Pour the melted white chocolate over the paper and spread with a spatula in another baking sheet.
Sprinkle the toppings of your choice over the chocolate. Set aside for 2 hours until set. Break into pieces.