Crush Oreos in a food processor or blender until very finely ground.
In a large mixing bowl, beat cream cheese till smooth. Add Oreo crumbs and mix till thoroughly combined. Cover and chill for about 30 minutes.
Roll into 1" balls and place on a waxed paper lined cookie sheet. Chill while you prepare the chocolate.
Melt shortening in a glass bowl in the microwave. Add chocolate chips. Cook at 50% power in the microwave, stirring every 30 seconds till smooth.
Dip truffles in the melted chocolate with a fork, then let excess chocolate drip off. I like to use a toothpick to push them off the end of the fork onto waxed paper. Let set till hardened.
If desired, you can decorate the truffles with green drizzle. Melt green mint chips or candy melts in a small ziplock bag in the microwave at 50% power. Snip a small hole in the corner and drizzle over the tops. Let sit till hardened.
Notes
You can substitute melting chocolate, white chocolate, or almond bark for the chocolate chips. Just omit the shortening.
If using chocolate chips, do not replace the shortening with butter or margarine! They contain water, and it will cause the chocolate to seize up and harden.