3 quarts muscadine grapes (I prefer the very dark, almost black, varieties)
5-6 C sugar
1/2 t butter

Cut each grape in half, remove and discard the seeds.
Separate the pulp from the skins.
Chop the skins using a food processor.
Puree the pulp also using the food processor. Add any juice to the pulp.
Cook the chopped skins, covered, on medium-low heat in just enough water to keep it from sticking, 20-25 min, till soft.
Boil down the added water till skins are just moist with barely any water left.
Add the pulp to the skins (you should have a total of about 2qts +1 C).
Add the sugar and butter,  stir, and bring to a boil.
Lower heat till the mixture is at a low, constant boil.
Cook till jelling point, 20-30 min. As mixture thickens, stir to prevent sticking.
Pour into hot jars, process in boiling water bath, 15 mins.