Puree the blueberry pulp in a food processor until it's smooth. This should take just one or two minutes.

In a six-quart (six-liter) stainless-steel or enameled Dutch oven, combine the pureed blueberry pulp, sugar, and all the other ingredients. 

Stir everything together until evenly combined.

Over medium heat, bring the mixture to a boil - make sure you're stirring often. 

Once it boils, you can reduce the heat and let the mixture simmer for about an hour. Stir it frequently. The mixture should begin to thicken and hold its shape when placed on a spoon.

Ladle hot blueberry butter into the hot jars, leaving a quarter-inch (.5 centimeters) of headspace. Remove air bubbles by running a plastic utensil along the inside of the jar.

Once the bubbles are removed, wipe the rims of the jars with a clean damp cloth.

Place the jars in a boiling water canner. Process them for 10 minutes (or 15 minutes if above 6,000 feet in elevation). 

After processing, turn off the heat, remove the lid, and let the jars sit in the canner for five minutes. 

Remove the jars and cool them on the counter for 24 hours. Check that the jars are sealed properly, then store.