Zest and juice the lemons to get 200ml. Place all of the zest, sugar, and cream into a pot and set over the stove on medium heat.
Bring mixture to a simmer, stirring continuously, until the sugar has dissolved.
Add the lemon juice, and bring back to a simmer, stirring to ensure completely mixed. Remove from the heat.
Strain the mixture through a fine sieve, and pour into small containers. Allow to cool to room temperature before covering with cling film, and chill in the fridge to set.
Allow to set in the fridge for a few hours, or overnight.