First we wash the plums, then we take out the seeds and place them in a pot. Add the powdered sugar and leave overnight covered with a lid, possibly in the fridge, to leave the juice.
The next day we boil the plums together with the lemon juice and rum essence (I measure the lid of the rum essence bottle, so I put 4 caps of essence).
Leave it to boil for about 2 hours, stirring from time to time, then place it in jars, put the lids on and then turn it upside down until the jam cools down.
It is stored in the pantry.