Line a 9×9 inch square baking pan with parchment paper with an overhang on the sides.
Place candy canes in a sealed bag and crush with a rolling pin until fine shards are formed.
Chop the Oreo cookies into bite-sized pieces using a sharp knife.
Melt the white chocolate in a heat-proof glass bowl over a pot of simmering water until smooth.
Remove from heat and stir in the peppermint extract.
Fold half of the chopped Oreos into the white chocolate mixture.
Pour the mixture into the prepared pan and spread evenly with a spatula.
Top with remaining crushed Oreos and crushed candy canes.
If using, drizzle with melted dark chocolate.
Allow to set completely at room temperature or in the refrigerator before breaking into squares.