Give the mussels another quick rinse to remove any little pieces of shell. Soften the garlic and shallots in the butter with the bouquet garni, in a large pan big enough to take all the mussels ...

To cook the mussels, heat the olive oil in a large skillet with a tight fitting lid over medium heat. Add the garlic and shallot ... Add the butter, shaking the pan to emulsify.