Combine the powdered sugar and cocoa powder. Pour cereal into a large bowl. Unwrap and melt Andes Mint on medium-low heat on the stove. Stir until smooth. Pour melted mints over cereal and gently fold until covered. Dump chocolatey cereal into a large plastic bag (or tupperware with a lid) and add powedered sure mix. Shake, shake, shake until coated! Pour onto a cookie sheet to cool.