Melt butter in a large microwaveable bowl.
Add marshmallows, stir to coat.
Microwave for about 2 minutes, or until puffy.
Stir. Add 1/2 tsp. peppermint extract.
Add cereal. Stir until coated.
Add 1/2 of the crushed candy canes. Stir until incorporated.
Spray a 9" x 13" pan with nonstick spray.
Pour cereal mix into pan and spread. I spray the top of the crispy treats with nonstick spray before spreading.
In a microwavable bowl melt milk chocolate chips in microwave on half power. Every microwave is different. I melted mine for about 2 minutes.
Spread chocolate on top of crispy treats. Let sit until firm.
Using same method melt white chocolate chips. After melted stir 1/2 tsp. peppermint extract into the white chocolate. Spread over milk chocolate layer.
Sprinkle remaining crushed candy canes over white chocolate layer. Press with the back of spatula to ensure they are embedded into the white chocolate.
Let sit until firm.
Cut into squares and serve.