In microwave, melt chocolate wafers with mint candy together for 1 minute, stir, and continue melting in 30 second intervals until smooth (about 2 minutes total).

In a large mixing bowl, combine cereal with melted chocolate. Fold with a large wooden spoon until all cereal is coated evenly.

In a large gallon-sized Ziploc bag, add powdered sugar. Spoon in chocolate-coated cereal. Seal and shake until coated. Pour onto wax paper and let chocolate set for about 20 minutes. Mix in M&M candies and store in an airtight container.