01 - Line a baking sheet with parchment paper or a silicone baking mat.
02 - Melt the dark chocolate in a heatproof bowl over a pot of barely simmering water, stirring frequently until smooth, or microwave in 30-second intervals, stirring in between until fully melted.
03 - Stir the peppermint extract into the melted chocolate until evenly combined.
04 - Pour the melted chocolate onto the prepared baking sheet and spread evenly into a roughly 9x12-inch rectangle about 1/4 inch thick.
05 - Sprinkle the crushed peppermint candies evenly over the chocolate layer.
06 - Gently press the peppermint pieces into the chocolate using the back of a spoon or your hands to adhere.
07 - Refrigerate for 45 minutes to 1 hour until the bark is firm and completely set.
08 - Once firm, break the bark into serving-sized pieces and store in an airtight container at room temperature or in the refrigerator.