Remove pits from washed cherries (I use my beloved cherry pitter). Chop some or all of them into pieces, you can leave some whole if you’d like...depending on how chunky you want your jam.
Place the cherries in a medium heavy-bottomed pan and add the sugar. Stir together and let sit for at least 30 minutes or up to 3 hours.
When ready to cook, turn the heat on and bring to a low boil. If the mixture is starting to foam, your can try to remove some of the foam with a spoon.
Once it comes to a boil, reduce the heat to medium-low and cook for 20 minutes. As you cook, the cherries will become soft and darken in color.
After the 20 minutes, add the vanilla, almond extract, lemon zest, lemon juice, and bourbon. The mixture should thicken slightly. Go ahead and add the butter (if using) as well and stir it in.
Let the jam cool for a couple minutes, then pour it into clean jars. Don't overfill them. Place the lids on (I recommend the metal ones for this) and screw on tight, then flip the jars upside down...the heat from the jam helps seal them.
Once cool, I tend to recommend refrigerating or freezing, though technically they'll be shelf-stable for a couple months. Once you open a jar, keep in the fridge and I recommend using within a month or so.