Wash and pit the cherries.

Place the cherries in a sauce pan with lemon juice, vanilla extract, and bourbon; bring to a simmer over a medium heat.

Mash the cherries leaving the fruit as chunky as you like.

Add the pectin and stir.

Increase heat to medium/high stirring constantly, and bring to a boil.

Pour all the sugar and keeping stirring whilst waiting for it to return to a hard boil; once boiling, cook for 1 minute.

Remove from heat and add the butter to reduce any foaminess.

Pour the boiling jam into sterilised glass jars (in the oven at 120°C for 5 minutes). Close them, turn them upside down to create the vacuum and let them cool until the next day or at least 12 hours.