01 - Line a 9x13 inch baking sheet with parchment paper.
02 - Melt dark chocolate in a heatproof bowl over barely simmering water or in 30-second bursts in the microwave, stirring until smooth. Stir in 1/4 tsp peppermint extract.
03 - Pour melted dark chocolate onto prepared baking sheet and spread evenly to about 1/4 inch thickness. Chill for 10–15 minutes until just set.
04 - Melt white chocolate using the same method as dark chocolate. Stir in remaining 1/4 tsp peppermint extract.
05 - Pour white chocolate over set dark layer and gently spread to cover quickly to avoid melting the layer below.
06 - Evenly sprinkle crushed peppermint candies on white chocolate and lightly press to adhere.
07 - Refrigerate for at least 30 minutes until completely firm.
08 - Lift bark from pan using parchment and break into irregular pieces by hand.