Line a baking sheet with parchment paper and set aside.
Before you start dipping the Oreos, blow or dust off any cookie crumbs you can. This will help your chocolate stay white and keep as many of the Oreo crumbs out as possible.
Take each white chocolate Reese's candy and cut in half so they will be ready to add right after the cookies are dipped. Set aside.
Place the white chocolate in a microwave-safe bowl. Microwave on high for about 30 seconds, then take the chocolate out and stir. Microwave again for 30 seconds, stirring afterwards. If needed, repeat the process until there are just a few unmelted pieces. Stir until completely melted.
Dip one Oreo in at a time into the white chocolate. Use a fork to turn the Oreo over and shake just a little to let any excess chocolate off the cookie.
Place the dipped Oreo cookies onto a baking sheet covered with parchment paper, add a half of a Reese's cup to the top, and allow to set up. Continue to dip until they are all finished.
Allow them to cool for 30 minutes, or until the chocolate is set. Once set, decorate as desired with melted dark chocolate, mini M&MS, sprinkles, etc.
Serve immediately or store in an airtight container at room temperature for up to 1 week. Enjoy!