Measure Cocoa Krispies into a bowl and set aside.
Coarsely chop the Andes Mints. Leave some bigger pieces
Spray a 9x13 pan and a rubber scraper (both sides) with cooking spray.
In a large, microwaveable bowl, combine the butter (cut up into smaller pieces) and all but 1/2 cup of the marshmallows. Microwave on high for about 1 minute and 30 seconds, until marshmallows are puffed up.
Quickly pour in the Cocoa Krispies and begin stirring to combine. Once the mixture is nearly all mixed together, add in the Andes Mints and the 1/2 cup marshmallows you set aside. Quickly combine the ingredients, then transfer mixture to the 9x13 pan and press treats into the pan, until level. (You want to do this quickly since you want the Andes chocolate to melt a little bit, but have some larger pieces remaining.)
Place pan in the fridge to cool while you prepare the drizzle.
Melt semi sweet chocolate chips and butter in the microwave for about 30-45 seconds. Stir gently and add in mint extract. Quickly transfer to a small baggie. Snip the corner off the baggie and, once you take the Krispie treats out of the fridge, drizzle the mint chocolate on top. You can also add some white chocolate drizzle on top of that like I did- it looks pretty!