Yum, both visually and taste-wise. Scientists from a Swiss company called Morphotonix have figured out how to print holographic designs onto chocolate bars without using any inks or dyes. Via NPR:
Typically, holograms are laser-imprinted onto a flat, metallic surface such as aluminum; the rainbow-colored hologram appears when light hits the surface at a certain angle (Think of the security sticker on the back of your credit card). But aluminum-drenched chocolate doesn’t sound very appetizing, so confectioners pour the chocolate into a mold etched with a patchwork of minuscule bumps, or microstructures, that bend light at specific angles — embedding a hologram directly onto its surface.