You’re welcome, Rozanne. The technique is much like flooding, except that you turn the piece over to put it on the cake. A few more quick tips, while the experience is still fresh in my mind.
1) the final result will be a reverse image in chocolate of the picture you’re using. So use a reverse image to begin with, if it’s important to your overall cake design to keep the original orientation.
2) I dissolved the powdered food color in a bit of melted cocoa butter first, then stirred it into the melted chocolate. My cake decorating store wanted to sell me a product made with oil, I think called parchment flakes, but I had the cocoa butter on hand.
3) For black, start with dark choc melts. It takes less food color to deepen brown than to start with white.
4) You probably know that chocolate doesn’t take kindly to food color with any water in it. That’s why I used powder.
5) And last but not least, place the piece very carefully. It’s fragile!
Labour-intensive but worth it to put a smile on a child’s face! Good luck with your project. I’ll look forward to seeing the results.