Divide the mussels in half.
Roughly chop one half and place in a food processor along with all the remaining ingredients, except the parsley.
Season and process the mixture until well chopped and creamy.
Tip into a bowl.
Set 2 mussels aside for garnish.
Finely chop the remaining mussels and stir into the paté along with the parsley.
Transfer to a serving bowl.
Thinly slice the 2 mussels and place on top, along with a sprig of parsley.
Serve at room temperature with crostini and vegetable crudités.