I used a bar of 87% dark chocolate: Dagoba Eclipse. Text on image above mistakenly says 86% dark.
I wanted to make a birthday present for a friend and wanted to make something edible. I love dark chocolate and always have some on me so figured I could try laser etching a bar. The first attempt is pictured above and I plan on trying it again with different settings on the laser and using a vector image that has more contrast between different parts to get a result that shows more detail. Epilog raster settings: 400dpi, 12% power, 100% speed.