Heat butter in a large pot over medium-high heat. Add the shallots and garlic and cook for 3 minutes.
Add wine, lemon, butter, parsley and salt. Bring it to a simmer and add the mussels. Cover the pot immediately. Cook until mussels open about 6- 8 minutes.
Divide the mussels and the juices into bowls. Best when served with crusty bread to soak up the sauce!