1. In a bowl, place the Camembert and butter and beat together until smooth.
2. Add the Petit Suisse and beat well to mix.
3. Add the cream, mustard and parsley; press into a lightly oiled mould.
4. To freeze: chill in the refrigerator, then open (flash) freeze until firm.
5. Remove from the mould and wrap in foil.
6. To freeze: wrap in a freezer bag or foil; seal and return to the freezer; label the bag as it makes it easier to distinguish.
7. To thaw: remove wrappings and arrange the mousse on a serving platter.
8. Thaw in the refrigerator overnight.
9. Arrange the dish in large serving platter and garnish the top of the mousse with grated cheese before serving.