This is a reverse redaction as no recipe has been found other then a mention of “plum jam with chicken” for a wedding feast. When redacting how a plum jam could have been made I referred to the recipes used for both carrot jam and squash jam. Both of these jams required sugar (some times honey) and spices. So I imagine that some where a recipe reads as follows for plum jam
“Take ripe plums, with out stones, and cut them up small. Add sugar and spices to a clean pot with them and cook till thickened.
8-10 ripe plums ½ cup sugar 1/3 cup of water
1/2 tsp ea: cinnamon, ginger, nutmeg, cloves, saffron, lavender
Since this is being based on a comment and the recipes from two other jams the spicing is up to the whim of the cook. Spices may have been added or may not; however I feel fairly confident that any cook who would add a whole cornucopia of spices to carrot jam would be more then happy to bring spices to brighten the flavor of plums in sugar.
I cut up the plums and added them to a pot with sugar and water. The plums can be cut up very small or if desired ground. I did use a cuisinart on part of the plums though I found that the plums left un-ground cooked down almost as well as the finely chopped plums. The spices were added at about the same time as the sugar.
The pot was allowed to simmer (NOT boil) for about an hour or until the jam thickened enough when stirred with a wooden spoon that a line drawn on the back of the spoon did not drip.I have tried this with roasted chicken.
The jam can be used with roasted chicken, I might even suggest a nice bit of roasted lamb as well. This makes for a very sweet dipped chicken!