Melt one package of candy melts in a microwavable glass bowl, according to package directions.
Drop an Oreo cookie into the candy melts and use a spoon to cover completely with coating. Use a fork to pick up the cookie from the bottom and lightly shake to remove excess coating.
Place on wax paper and immediately and sprinkles and other decorations. Repeat step 2 until color is gone. Repeat steps 1 and 2 with other colors of candy melts.
Notes
I used black, bright white, purple, orange, and bright green candy melts.