Cool until able to handle. Scoop out the flesh and mash with a potato masher, puree in a blender or processor, or push through a fine sieve. If the puree is too watery, drain in a colander lined with cheesecloth, folding the cheesecloth over the puree and weighing down with a plate. Puree will keep up to 5 days in the refrigerator and up to 6 months in the freezer. Pumpkin should be fully mature with a hard rind and stringless flesh.
Small pumpkins give the best results.
Wash, remove seeds, and peel. Cut flesh into 1-inch cubes. Boil 2 minutes in water. Do not mash or puree. Fill jars with cubes and cooking liquid, leaving 1-inch headspace.