Heat ½ cup of the cream in a saucepan until nearly boiling. Pour over the eggs and sugar mixture and stir constantly. Return custard to the saucepan and stir constantly while heating on low heat until it coats the back of a spoon. Do not allow it to boil as the eggs will scramble. Remove from the heat and pour into a bowl. Place a piece of clingfilm onto the custard to avoid a skin forming and stand until cold.