01 - Pour heavy cream and granulated sugar into a medium saucepan. Place over medium heat, stirring gently until sugar completely dissolves.
02 - Continue heating until the cream just begins to simmer, watching carefully to prevent boiling. Remove from heat immediately.
03 - Stir in freshly squeezed lemon juice and grated lemon zest. The mixture will naturally thicken as the acid reacts with the cream proteins.
04 - Let the mixture cool at room temperature for 10 minutes, allowing flavors to meld.
05 - Distribute the mixture evenly among 4 individual ramekins or dessert glasses.
06 - Refrigerate for at least 3 hours until the posset achieves a firm, silky consistency similar to pudding.
07 - Serve chilled with optional garnishes of fresh berries, additional lemon zest, or shortbread cookies.