1. Rinse the plums in cold water. Cut them in half and pit them. 
2. Place the plums and sugar in the jam basin, mix and leave to macerate for a few hours (3 to 4 hours).
3. Bring to a boil. From this moment, count the cooking time: 7 minutes with gelling sugar, otherwise 15 to 20 minutes. Keep the heat high and stir often.
4. At the end of cooking, add and mix the 5 cl of plum brandy.
5.  Check the cooking by pouring a few drops onto a cold plate then tilt the plate: the jam should flow slowly.
6. Skim then proceed without delay to potting.
7. Replace the lid and place the jars upside down for 1 minute, then turn them right side up to let them cool.

Brandy is optional but adds flavor and helps preserve the plum jam.

Tips: 

• You can add a vanilla bean or cinnamon stick to your plum jam for extra flavor.

• Adjust the sugar if the plums are very juicy.