Michigan State University Extension
Preserving Food Safely - 01600550
Butters can be made from most fruits or fruit mixes. Apple is the most common butter, but apricot, crabapple, grape, peach, pear and plum also make good butters.
The fruit is prepared similarly to preserve fruit, but the soft fruits should be mashed and the hard ones diced or chopped. Add water to cook the fruit soft enough to be pressed through a food mill or sieve to make smooth butter- texture.
Use 3/4 cup of sugar to 1 cup of fruit pulp for butters. Do not make a single batch larger than four cups of pulp plus added sugar. Stir constantly when heating; the mixture will stick easily. A heavy pan will work better for this than a light, thin one. Dissolve the sugar on low heat then bring the mixture to a rapid boil and cook until thick.
Skim off any foam from the top of the pot and then pour the mixture into jars. Process butter in a boiling water bath canner.