01 - Pour heavy cream and granulated sugar into a medium saucepan. Place over medium heat, stirring gently until sugar completely dissolves.
02 - Bring the cream mixture to a gentle boil, then reduce heat to maintain a steady simmer. Cook for 3 minutes, stirring occasionally to prevent overflow.
03 - Remove saucepan from heat. Stir in lemon zest and juice until thoroughly combined.
04 - Let mixture cool for 5 minutes. For a smoother texture, strain through a fine sieve into a pitcher to remove zest pieces.
05 - Divide mixture evenly among 4 small serving glasses or ramekins.
06 - Refrigerate for at least 3 hours or until completely firm and set.
07 - Top each posset with fresh berries and mint leaves just before serving.