Stir together the plums and sugar in a large saucepan. Bring to a boil over medium heat.

Reduce the heat slightly to maintain a low boil. Stir often and continue to cook the compote until the fruit is very soft and begins to break down. Gently smash it as you stir. This can take 5 to 20 minutes, depending on firmness of the plums.

Once the fruit has softened and a thick syrup forms around it, remove it from the heat. Stir in the cinnamon and salt. Transfer to a jar, cover and refrigerate until chilled, at least one hour. Serve over ice cream.