Turn your Sous Vide to 80 degrees Celsius (176 degrees Fahrenheit).
Crush some digestives and place them at the bottom of the jars, creating a 0.5 - 1cm thick base.
Whisk Philadelphia and sugar together using a hand mixer. Add the eggs one at a time. Once well blended, add the cream, vanilla essence, and rum essence gradually. Once everything is mixed into a uniform liquid mass, pour it into the jars. It's normal for it to be very liquid. Then, put lids on the jars and secure them - you might want to use a rubber band around the lids.
Place the jars in your preheated Sous Vide at 80 degrees Celsius (176 degrees Fahrenheit) for an hour and a half.
After an hour and a half, take the jars out - the mixture should now be firm but airy. Be careful, an 80-degree Sous Vide is surprisingly hot.
Place the jars in ice water to cool them down faster, then move them to the fridge once they've sufficiently cooled.
They can last for 7 days in the fridge. When you wish to serve them, just remove the lids and top with some crushed "mock turtle" chocolates and some crushed digestives.
Enjoy and bon appétit.