Add sliced plums (pits and stems removed) to a pot along with sugar, vanilla, star anise, cinnamon, and water and bring to a simmer.
Let simmer until plums have softened and the liquid looks syrupy, about 10-15 min.
Remove the star anise from the mixture and add the rest of the cooked plum mixture to a blender or food processor and process until smooth. Alternatively you can use an immersion blender.
Serve desired amount warm over vanilla ice cream and enjoy!
Note: This plum syrup will stay fresh in the refrigerator for up to two weeks. Can simply reheat when ready to serve.