01 - Line a 9x13 inch baking sheet with parchment paper.
02 - Melt semisweet or dark chocolate in a heatproof bowl over simmering water or in short intervals in the microwave, stirring until smooth.
03 - Pour melted dark chocolate onto the prepared sheet and spread evenly to a thickness of 1/4 inch. Refrigerate for 15 minutes until set.
04 - Melt white chocolate using the same method and stir in peppermint extract if using.
05 - Pour melted white chocolate over the set dark chocolate and gently spread to cover.
06 - Immediately sprinkle crushed peppermint candies evenly over the white chocolate layer, gently pressing them in with parchment if necessary.
07 - Refrigerate for at least 1 hour until fully set.
08 - Break into pieces and store in an airtight container at cool room temperature for up to 2 weeks.