Line a baking sheet with parchment paper.
Melt the semisweet chocolate in a heat-safe bowl over a pot of simmering water or in the microwave in 30-second intervals until smooth.
Spread the melted semisweet chocolate into an even layer on the prepared baking sheet.
Refrigerate for 20 minutes until the chocolate is set but not completely hard.
Melt the white chocolate in a clean bowl until smooth, stirring in the peppermint extract once melted.
Spread the white chocolate evenly over the semisweet chocolate layer.
Immediately sprinkle the crushed candy canes over the top of the white chocolate.
Refrigerate for at least 45 minutes until the bark is completely firm.
Break or cut the bark into small pieces and serve at room temperature.