Mussel gratin a really quick and easy appetizer (cleaning the mussels apart!) that you can prepare in ten minutes after the arrival of your guests. Serve hot as soon as they’re ready, and let your guests sample them while you finish preparing lunch or dinner. They act as a real ‘apristomaco’ (‘stomach opener’) and will enchant everyone who tries them. And since the mussels are well-cooked, you can also give them to children at home with an easy conscience. So, to work!