Wash and rinse cranberries removing any stems and bruised berries.
Put cranberries in a pot with 2 cups of water and heat to boiling.
Continue to boil until cranberries pop open. When the cranberries pop open, the pectin is released from the fruit which will allow natural thickening.
When most of the cranberries have burst open, mash them in the pot. I use my stick wand mixer to puree them in the pot and this works great.
Now add the sugar and allspice according to your taste.
Let this boil for at least 5 minutes and test.
To test for readiness: Place a small amount of the sauce on a glass plate and run your finger down the middle of it. If it runs back together, continue to boil a little longer and retest. If it stays separated, it's ready. Remove from heat and place in the glass container you wish to serve it from or in a glass jar with a lid.
Let chill until completely set, at least 3 hours.