In a medium saucepan, combine the heavy cream and granulated sugar.

Heat the mixture over medium heat, stirring constantly, until the sugar dissolves completely and the cream comes to a gentle boil.

Let the cream simmer for 2-3 minutes, continuing to stir to prevent scorching.

Remove the saucepan from heat and stir in the freshly squeezed lemon juice and lemon zest until well combined.

Pour the mixture into serving glasses or ramekins and allow them to cool to room temperature.

Once cooled, cover the glasses with plastic wrap and refrigerate for at least 4 hours, or until the posset is set and has a creamy, pudding-like consistency.

Before serving, garnish with fresh berries or additional lemon zest, if desired.