Prepare a baking sheet lined with parchment paper.
Melt the dark chocolate in a double boiler over simmering water.
Stir until smooth, then remove from heat.
Pour the melted dark chocolate onto the prepared baking sheet and spread evenly.
Refrigerate for about 20 minutes until set.
Melt the white chocolate using the same method and stir in the peppermint extract.
Pour the white chocolate over the dark chocolate layer.
Sprinkle crushed peppermint candies on top and gently press them in.
Refrigerate again for 40 minutes until fully set.
Once set, break into pieces and serve.