In a large mixing bowl, combine Corn Chex, Rice Chex, mini pretzels, M&Ms, and crushed candy canes.
Melt white chocolate chips in a microwave-safe bowl, stirring every 30 seconds until smooth.
Stir in peppermint extract to the melted chocolate.
Pour the white chocolate over the cereal mixture and toss gently to coat everything evenly.
Spread the mixture on a parchment-lined baking sheet.
Add sprinkles if using, and let it cool completely until the chocolate sets.
Break into pieces and store in an airtight container.