While running the processor, gradually pour 5 tablespoons juice down feed tube until mixture forms a ball.
Gradually pour the hot liquid onto the cornflour and sugar, whisking all the time until smooth.
If using heavy cream, gradually pour in the sugar.
With the machine running, gradually pour in the milk.
With the motor running, pour in the cream gradually.
With mixer running, gradually pour in milk and cream.
Gradually pour half the hot liquid over the yolks, whisking to combine.
Gradually pour in the sugar syrup, beating constantly until cool and thick.
Increase the speed of the machine and gradually pour in the butter.
With mixer on medium high, add salt, and gradually pour in sugar.