Squeeze the fruit to let out some of it's juices.
Heat in a large saucepan, simmer for 15-20 minutes, stirring, until fruit has
broken down and is soft.
Puree in a food processor until silky. You can strain it to remove any seeds at
this point if you like. I use a VitaMix which purees the seeds.
Return to heat, slowly add sugar, stirring. Bring to a simmer and let thicken,
stirring often, for about 45 minutes to an hour, until reduced and coats a
spoon. To make 'butter', continue cooking until thick like jam.
Pour hot puree into jars, let cool, and refrigerate.
Or, use a water bath canning process: pre-simmer the cans and lids until
hot. Add puree, leaving space at the top. Screw on lid and ring, place in the
simmering water, bring to a soft boil, cover, let boil for 10 minutes. Turn off
heat, wait 5 minutes, remove to a rack or a paper towel, and let rest 12 hours
or overnight. The lid when pressed should be firm when sealed. If not, use it
and refrigerate.