Plum Jam (Pflaumenmus)

Every time I go to Gustavs or Rheinlander on Sandy Blvd, in Portland, I always ask for a side of their famous (in my book) plum jam. And for the entire time I am there, I forget about my "no bread after breakfast" rule, because I can't stop eating their sourdough rolls with salty butter and the delicious plum jam! Well... after many attempts of finding a replica, I finally got it! Here it is:

3.5 kg plums, pitted and halved
700 grams white sugar
2 cinnamon sticks
7 cloves
2 nutmegs
1/8 tsp ground nutmeg

Place plums, sugar and spices in a large bowl, and cover with plastic wrap and leave overnight. In a heavy pot, bring to a boil, and then reduce the heat to a slow simmer for 1 1/2 hours. Remove cinnamon sticks and nutmegs and press the jam through a food mill or a siv, then pour into a tray and bake at 350 F for about 1 1/2 hours with the door slightly open so the excess liquid evaporates. Place in sterilized jars and cover with a towel overnight until it has cooled.
Enjoy!