Add the cherries and sugar to a large, flat-sided skillet (sautoir) or Dutch oven. Stir and allow the mixture to macerate for at least 15 minutes, to allow some liquid to release from the cherries.
Turn the heat to medium and allow the liquid to come to a simmer while stirring periodically. Stir in the lemon juice and cherry brandy.
The skillet will continue to fill with liquid as it is released from the cherries. Continue stirring the jam frequently as it simmers, until most of the liquid has evaporated or thickened, 30 to 45 minutes. Remember that the jam will continue to thicken once it cools.
Once the jam is thick, remove it from the heat. Can, freeze for 3 months, or store in the refrigerator for up to 1 month.
Notes
Use a cherry pitter and kitchen gloves to for a tidy, faster pitting process.To test if the jam has properly gelled, you can place a small plate in the freezer before getting started. When you suspect that the jam is ready, place a very small spoonful on the chilled plate and return it to the freezer. After 3-4 minutes, check to see if the jam has gelled. With a bit of practice, you'll be able to tell if the jam is ready just from looking at it.