01 - In a medium saucepan, combine the heavy cream and sugar. Place over medium heat and stir gently until the sugar dissolves completely.
02 - Bring the mixture to a gentle boil, then reduce heat and simmer for 3 minutes. Stir occasionally and watch carefully to prevent overflowing.
03 - Remove from heat. Stir in the lemon zest and juice. Mix thoroughly until well combined.
04 - Allow the mixture to cool for 5 minutes, then strain through a fine sieve into a pitcher to remove zest for a smoother texture.
05 - Pour the mixture evenly into 4 small serving glasses or ramekins.
06 - Refrigerate for at least 3 hours, or until completely set and firm.
07 - Just before serving, top with fresh berries and mint leaves if desired.