Wash, stone, and roughly chop the plums. Place them in a very large, wide, and deep pot. Add 60 ml/ ¼ cup water and stir. Heat slowly. Once it starts to boil, turn the heat to medium-low and cook, stirring occasionally, for 30 minutes or until the fruit is completely soft and broken down.

Blend with an immersion blender until smooth. Cook for another 10 minutes. The butter will start to bubble immediately and the bubbling will be quite violent during the first 5-6 minutes. It is better to cover the pot, leaving a crack open, during this time. Once the bubbling has calmed down, remove the lid.

Add the spices and the sugar and mix well. Continue cooking on low heat, uncovered, for another 30 minutes to 1 hour until the Pflaumenmus has thickened to your liking, stirring every 5 minutes or so making sure that you scrape the bottom of the pot as well.

Mine is cooked for 30 minutes and it is really fruity. The longer you cook it, the sweeter and more caramelized it will become. If you like more of a caramel note, you can cook it for longer, a total time of 2-3 hours.

Ladle into clean jars leaving about 0.6 cm/ ¼ inch headspace. Wipe the rims and place the lids on. Can in a water bath canner for 10 minutes. Leave to rest for 5 minutes. Carefully remove using a jar lifter and wearing mitts. Place on folded kitchen cloths and leave, undisturbed, to cool completely.