In a saucepan, combine the heavy cream and sugar over medium heat.
Stir continuously until the sugar has completely dissolved.
Bring the mixture to a gentle boil and let it simmer for 3 minutes.
Remove the saucepan from the heat and allow it to cool slightly.
Add the freshly squeezed lemon juice and lemon zest to the cream mixture.
Stir well until fully combined.
Pour the mixture into serving glasses or ramekins.
Refrigerate for at least 4 hours, or until set.
Once set, remove from the refrigerator and garnish with mint leaves if desired.
Serve chilled and enjoy your creamy lemon posset!