Place the fruit in a large wide pot together with the apple juice. Bring to a boil, turn the heat down to medium-low and cook for 2 hours, stirring occasionally, every 10-15 minutes or so.

Add the sugar, stir well and continue cooking for 30 minutes, stirring more often now and making sure you scrape the bottom and the edges of the pot well while stirring to prevent the cherry butter from catching. A large, wide cooking pot will accelerate things a little bit.

The cooking time depends on the quantity of fruit you are turning into butter and on the size of your cooking pot. If you cook a smaller amount of cherries, you will need less time, if cooking more cherries it might take longer.

Puree the fruit with an immersion blender.

If using spices, you can add them now.

Carefully pour the cherry butter into sterilized jars using a jam funnel.

Place the closed, hot jars in a large pot lined with a textile kitchen cloth and fill the pot with hot water. The water should come about halfway up the sides of the jars. The jars should not touch each other, neither should they touch the
bottom of the pot, they should all fit snugly into the pot and onto the folded kitchen towel.

Boil the jars for about 20-25 minutes. Carefully lift them out of the water, place them on another kitchen towel on the counter and let them get cool.

Store in a cool, dark place