01 - In a medium saucepan, add heavy cream and caster sugar.
02 - Gently heat over medium, stirring continuously until sugar is fully dissolved.
03 - Bring to a gentle boil; allow to simmer for 3 minutes while stirring occasionally to prevent overflow.
04 - Remove saucepan from heat and let cool for 2 minutes.
05 - Stir in lemon zest and lemon juice until the mixture is thoroughly combined and slightly thickened.
06 - Distribute mixture evenly among 4 small serving glasses or ramekins.
07 - Bring to room temperature, then refrigerate for a minimum of 3 hours, or until fully set.
08 - Just before serving, garnish with fresh berries and a biscuit of choice if desired.