Set a large saucepan over a medium heat. Melt the butter. Add the chopped shallot and garlic and cook for a couple of minutes. They should soften but not brown. Add the wine and mussels, turn the heat up to high and cover tightly with a lid. Allow the mussels to cook for 3-4 minutes, shaking the pan from time to time to ensure they cook evenly. Discard any that have not opened.
Remove the pan from the heat to stop the mussels cooking any further. Sprinkle with chopped parsley, then spoon them into warmed bowls and pour over the pan juices.
Serve with lots of crusty bread.