Grease an 8x8 baking dish and set aside. I like to put parchment paper down in my pan so I can cleanly pull the marshmallow treats right out and cut them in the end.

Add cookies to a large plastic Ziploc bag. Use a rolling pin to crush the cookies into large chunks. You can also use a food processor instead. Place them into a large bowl.

In a medium saucepan, add the butter and cook on low until melted.

Add the marshmallows and 1 tablespoon of milk to the butter. Continue to cook on low heat, stirring often until marshmallows are melted and smooth.

While the marshmallows are melting, place the white chocolate chips and remaining milk in a separate glass bowl. Microwave the bowl in 30-second increments and stirring in between until fully melted.

Pour the white chocolate over the crushed cookies, add in the peppermint extract or crushed candy cane, and stir until fully combined.

Once the marshmallows are melted, add the marshmallow mixture to the cookie mixture and stir to combine.

Pour the mixture into the 8x8 pan using a piece of parchment paper or a spatula to press the mixture down evenly.

Top with sprinkles and additional crushed cookies if using.

Chill in the refrigerator for at least 1 hour before cutting into squares, then enjoy!