In a medium saucepan, combine the plums, sugar, and water. Bring to a boil over medium-high heat and cook for 5 minutes, stirring occasionally.
In a small bowl, whisk together the cornstarch and 2 tablespoons of cold water. Pour the mixture into the saucepan and stir until the mixture thickens, about 2 minutes.
Remove from the heat and stir in the vanilla extract and cinnamon. Transfer to a serving bowl and let cool.
Serve the plum flummery warm or at room temperature.
Interesting Facts
Plum flummery is a traditional British dessert that has been served in homes for centuries.
It is a quick and easy dessert that can be made in less than 30 minutes.
Flummery is a type of soft, jelly-like dessert made with fruit and thickened with cornstarch.