<p>Hot chocolate or 'cocoa' bombs are the new sweet must-have. Having initially taken social media by a storm, their popularity means they are now sold in store and on-line and are on everyone's hygge wish-list! But just what are they? Basically, they are a piñata that melts in your cup? Hollow spheres of chocolate that you put into a mug or cup and when you pour in hot milk, the chocolate melts to create a hot chocolate drink and also magically ...