When you are ready to finish assembling the pudding, remove both bowls from the freezer. In order to remove the dish that is creating the space for the cherry core, you need to carefully pour boiling water to about three-quarters full in the empty soufflé /ramekin, trying not to get the frozen mixture wet. Wait a minute or so before carefully spooning the water out of the bowl, into the sink. You will now be able to safely remove the bowl/ramekin from the large bowl and then spoon the cherry mixture as the core of the pudding. Return to the freezer for at least 30 minutes, and up to 2 weeks.