Lemon Posset

0 Wash and dry the lemons well. Slice them in half lengthwise, then carefully cut around the inside of each lemon and scoop out the pulp without puncturing the rind.
1 Squeeze the removed lemon pulp and measure out 6 tablespoons fresh lemon juice. Set aside.
2 Arrange the hollowed lemon halves in a muffin tin or another dish that keeps them upright. Place them in the freezer while you prepare the filling.
3 Add the heavy cream, sugar, salt, and vanilla to a medium saucepan. Bring to a boil over medium heat, stirring occasionally and watching carefully so the cream does not boil over.
4 Once boiling, reduce the heat and simmer for a full 5 minutes, stirring occasionally.
5 Remove the saucepan from the heat and allow the mixture to cool for a few minutes. Stir in the lemon juice. The mixture should begin to thicken almost immediately.
6 Remove the lemon shells from the freezer and carefully pour the posset mixture into each shell.
7 Refrigerate for at least 3 to 4 hours, or overnight, until completely chilled and set.
8 Garnish with a small mint leaf before serving, if desired.