Heat the Cream and Sugar – In a medium saucepan, combine 600ml of double cream and 150g of caster sugar. Place over low heat, stirring gently until the sugar completely dissolves.
Bring to a Boil – Increase the heat slightly and bring the mixture to a gentle boil. Stir occasionally and allow it to simmer for about 3 minutes.
Add the Lemon Juice – Remove the pan from heat and stir in 75ml of fresh lemon juice. Stir thoroughly to allow the acidity to thicken the mixture.
Cool and Set – Let the mixture cool slightly before pouring into serving glasses or ramekins. Allow it to sit at room temperature for 10 minutes.
Chill – Cover with cling film and refrigerate for at least 2 hours, or until fully set.
Garnish and Serve – Optionally, top with extra lemon zest or serve with shortbread biscuits. Enjoy!