Plum Butter

Directions

1. 1
   Sterilize jars and lids .
2. 2
   Freeze several small plates to use for testing butter.
3. 3
   Scrape seeds from vanilla bean into a 5- to 6-quart heavy pot.
4. 4
   Add pod and stir in remaining ingredients.
5. 5
   Slowly bring to a rolling boil over moderate heat (this will take about 15 minutes), stirring frequently.
6. 6
   Boil, uncovered, stirring frequently, until plums are tender, about 5 minutes.
7. 7
   Discard pod.
8. 8
   Puree plums with liquid in batches in food mill set over a bowl.
9. 9
   Transfer puree to pot and simmer over low heat, stirring and scraping bottom of pan frequently, until very thick, about 1 1/2 to 2 hours.
10. 10
    (To test for doneness, drop a spoonful of plum butter on a chilled plate, then tilt; the mixture should not be runny.
11. 11
    It should be about as thick as jam.)
12. 12
    Drain jars upside down on a clean kitchen towel 1 minute, then invert.
13. 13
    Ladle plum butter into jars, leaving 1/4 inch of space at top, then run a thin knife between plum butter and jar to eliminate air bubbles.
14. 14
    Seal, process, and store filled jars , boiling plum butter in jars 10 minutes.
15. 15
    Let plum butter stand in jars at least 1 day for flavors to develop.