Fill two small pots with water halfway full. Bring to a simmer.

Place the dark chocolate in a small bowl. Place the white chocolate in a small bowl. Set each bowl over a pot and leave undisturbed until you see the chocolate beginning to melt, about 5 minutes.

While the chocolates melt slowly on the stovetop, unwrap the candy canes, then place in a food processor. Purée until the candy canes are nearly dust or until they are chopped to a coarseness of your liking.

Stir the dark chocolate with a spatula until smooth, then add ¼ teaspoon of peppermint extract, and stir until completely smooth.

Line a 9×13-inch or 10×14-inch pan with parchment paper. Spread the dark chocolate into the pan, then transfer to the fridge for 10 to 12 minutes or until the chocolate just sets.

Stir the white chocolate with a spatula until smooth, then add the remaining ¼ teaspoon of peppermint extract, and stir until completely smooth.

Spread the melted white chocolate over the dark chocolate. Sprinkle roughly ¼ cup of the peppermint dust over the surface.

Return to the fridge for 20 minutes. Remove from the fridge and let sit at room temperature for another 20 minutes.

Cut into neat triangles or break into shards. To cut into triangles, first trim away the rough edges. Then cut the bar roughly into 2-inch squares. Finally, cut each square in half on the diagonal to create triangles. Return the bark to the fridge for another 20 minutes to firm up.

You can store the bark at room temperature in an air-tight container or in the fridge for up to 3 weeks.