Crush the 100 grams peppermint candy or candy canes.
Add the 70 grams cultured unsalted butter, 220 grams marshmallows, and 1 teaspoon vanilla to a microwave-safe bowl and heat at 600 watts for about 2 minutes. Be sure to keep an eye on it so that it doesn't spill over.
Stir the mixture until the butter and marshmallows are combined into a smooth cream. If your marshmallows weren't fully melted, throw them back in the microwave for a bit.
Add the 180 grams cornflakes, 120 grams white chocolate, and ⅔rds of the peppermint candy. Stir this around until the cornflakes are evenly coated with the marshmallow mixture, and the peppermint candy and chocolate are evenly distributed. You want the chocolate to melt a bit, but not entirely.
Shape the Peppermint Bark into whatever shape you want it to set. You can make round cookies, or press the mixture into a sheet pan.
Sprinkle the remaining peppermint candy on top to garnish.
Refrigerate the Peppermint Bark until it's set. If you're making bars, you can cut them up at this point.
Wrap them individually or place them in an airtight container to store them.