The concept is fairly simple: an edible chocolate sphere packed with hot chocolate mix and (optional – but highly recommended) tiny marshmallows. The chocolate shell is typically kept very thin so that when one dunks it in a cup of hot milk – or places it in a cup and pours boiling milk over the top – the “bomb” melts into the liquid, leaving little marshmallows floating on top. Many have started recording these Instagram-worthy “explosions” for social media. Indeed, a cursory scan of the hashtag #hotchocolatebombs reveals more than 85,000 posts on the photo-sharing platform alo...