2tablespoonsvegetable shortening (such as Crisco)divided
20chocolate sandwich cookies (such as regular or mint Oreos)
1cupmint chips OR Andes mint bits
1cupgreen M&Msregular or mint
Line a large jellyroll pan or cookie sheet with wax paper. Roughly chop sandwich cookies into quarters.
Pour semi-sweet chocolate chips and 1 tablespoon shortening into a microwave-safe bowl. Microwave for 1 minute; stir chocolate well. Microwave for another 30 seconds; stir until chocolate is smooth. (If necessary, microwave in additional 15-second increments, stirring between each one, until chocolate is completely melted and smooth.)
Spread melted chocolate in a thin layer onto wax paper. Sprinkle with chopped cookies and mint chips (or Andes bits), pressing them down into melted chocolate in a single layer.
Melt white chocolate chips with 1 tablespoon shortening in a clean bowl by repeating the above process, but microwave for only 15 seconds after the initial 1 minute since white chocolate melts more quickly than regular chocolate.
Carefully drizzle white chocolate over cookie layer and spread in an even layer. Sprinkle with M&Ms, pressing them down into the white chocolate, and then fill in any bare areas with green sprinkles.
Refrigerate until chocolate is hard. Carefully break into large chunks and enjoy!
The shortening is added to the chocolate chips to help the chocolate harden once cooled. If you prefer, you may use dipping chocolate/candy coating instead of chocolate chips plus shortening.