This is one of those absolute classics, and deservedly so. This is so classic that I really can’t see any reason to cook mussels any other way (except as an ingredient to another dish such as Paella , of course). If you’re having mussels as just, well, mussels, then this is the way to cook them.
Wash the mussels under cold running water in a sink, removing the beards with a paring knife. Do not scrub the shells – apparently the colour will taint the juices in cooking. Discard any broken mussels or mussels that remain open when tapped sharply a few times.
Melt the butter in a casserole (one that has a tight-fitting lid) that is plenty big enough for the mussels with room to spare. Toss in the shallot, garlic and thyme (if using) and sweat for a minute. Add the wine and bring to simmering point to drive off the alcohol.
Add the mussels, cover with a lid and cook for 3 minutes or until the mussels open. Hold the lid and shake the pan a time or two to stir the mussels up a bit. Discard any mussels that do not open.
Add the cream and parsley and stir well. Do not season – the salty mussel juices mixed with the wine are all you will need.
Serve with crusty French bread and/or, for the total French experience, frîtes .