Line a baking sheet with parchment paper, ensuring it covers the entire surface for easy removal later.
In a microwave-safe bowl, place the white chocolate chips. Microwave in 30-second intervals, stirring in between, until fully melted and smooth, about 1-1.5 minutes total.
Stir in the peppermint extract to the melted white chocolate, mixing well to incorporate the minty flavor.
Add the crushed peppermint candies to the melted white chocolate, reserving a few tablespoons for topping. Stir until well combined.
Pour the white chocolate mixture onto the prepared baking sheet. Use a spatula to spread it into an even layer about 1/4 inch thick.
If using dark chocolate, melt it in the microwave following the same method as the white chocolate. Once melted, drizzle it over the white chocolate layer using a spoon or a piping bag for finer control.
Sprinkle the reserved crushed peppermint candies evenly over the top of the chocolate layer, ensuring they stick to the melted surface.
Place the baking sheet in the refrigerator for about 2 hours or until the chocolate is fully set.
Once solid, remove the bark from the baking sheet and break it into pieces of your desired size.
For an extra touch, sprinkle a pinch of sea salt over the pieces for a contrast in flavors.
Notes
For a richer flavor, consider adding more dark chocolate for drizzling.