Break white chocolate up into small pieces and melt in a microwave at 30 second increments until fully melted, stirring in-between melting times.
While the chocolate is melting, gently remove/twist off one cookie side from each Oreo. Place a lollipop stick in the middle of the OREO creme, then place the cookie back.
Gently dip each OREO into the melted white chocolate, coating both sides.
Sprinkle with sugar decorations, and let dry on a sheet of wax paper.
Notes
This makes 12-15 OREOS. I have found that Double Stuffed OREOS work best. The regular ones tend to be too thin to hold the lollipop sticks and the cookies break apart easier. Be very careful during the dipping process, as cookies can break during this step. If you've never made these before, or you're making these with little kids, be prepared with extra cookies in case some break. I've found that they tend to just have one side of the OREO cookie break in half, in which case you can use the melted chocolate to hold together the cookie.