Damson in distress

Leafing through the newspaper with my morning coffee (heaven), I came across an article about plums which are in season right now and went off in search of a suitable recipe for jam. I'd like to report that I chose this one because of my interest in the cuisine of the Thüringen region. When in reality the following recipe got the nod due to my congenital maths deficiency. Since I am just cooking for Mr. Big and me, and we have to be economical with fridge and cupboard space, I am often forced to halve and quarter recipes. Shamefully, this damsel is often left in mathematical distress . As you can see the proportions for this jam recipe are so simple that on halving, my overworked calculator was proudly left in the drawer.

The variety of plum I've used is known as a damson, which is slighty elongated with a blue-ish skin and yellowy flesh. But the regular plum can be used just as well.

Plum jam (Thüringer Art)
1kg plums
100g caster sugar
100g brown sugar
1 stick of cinnamon
a few walnuts

Wash the plums, remove the stones and leave overnight marinating in just the caster sugar. Then add the brown sugar, cinnamon stick and the walnuts, put in a saucepan and cook over a moderate heat until thick, about 30 minutes.
Remove the cinnamon stick and fill into 2 glass jars.