Combine all ingredients in a large stock pot. Cook on medium heat, stirring occasionally, until sugar, cornstarch and butter are melted.
Ladle into hot sterilized quart jars to within ½ inch of top, seal with new sterilized lids, and process full jars in boiling water bath canner for the appropriate amount of time for elevation.
Serving suggestions: Use as mincemeat pie filling (one quart per pie) with a single crust or double crust pie. Bake at 425 degrees for 35 minutes. Can also serve hot over ice cream.