Remember to freeze the base of your ice cream machine the night before you want to use it.
Whisk the condensed milk and double cream together until smooth. Take the ice cream base out of the freezer and assemble the machine. With the motor running, pour in the milk mixture and let it churn for 30 minutes.
Break up the cake into small bite size chunks. Stir them through the churned ice cream mix and pour the mixture into the ice cream pot or tubs. Freeze for at least four hours, or overnight, then serve.