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. Reduce heat and simmer for exactly 3 minutes, stirring occasionally to prevent overflow. Watch carefully during this stage.
03 - Remove saucepan from heat immediately. Stir in fresh lemon zest and juice, mixing thoroughly until completely incorporated.
04 - Let mixture cool for 5 minutes. For a smoother texture, strain through a fine sieve into a pouring jug to remove lemon zest pieces.
05 - Divide mixture evenly among 4 small serving glasses or ramekins, filling each container.
06 - Refrigerate for at least 3 hours or until posset is completely set and firm to the touch.
07 - Top each posset with fresh berries and mint leaves immediately before serving.