Blueberry Butter.

I made blueberry butter today too.  I found this recipe on line, I've put my variations in ().

Slow Cooker Blueberry Butter
makes approximately 3 1/2 pints of butter
8 cups of pureed blueberries (once pureed that is ALOT of blueberries! I only had roughly 3 cups)
2 cups sugar (used a little less than 1 cup)
1 lemon, zested (1/2 a lemon, juice and zested)
2 teaspoons cinnamon (1 teaspoon)
1/2 teaspoon grated nutmeg (1/4 teaspoon)

Put the pureed blueberries in a slow cooker. Place a lid on the pot and turn it on to low. After about an hour, give it a stir (it's think and creamy at this point). At this point, you want to use something to prop the lid a bit. I found that laying a wooden spoon across the rim of the cooker and then placing the lid on gave it just enough room to let the steam evaporate.
I slow cooked it for about 6 hours total.  At the beginning of hour five, I added the spices and the sugar, removed the lid completely and turned the heat up to high, in order to speed the cooking down. (I goofed and added the sugar and spices after the first hour, but I'm pleased with how it turned out)
Once it’s cooked down sufficiently, pour into jars (leave a good 1/2 inch of head space), wipe rims, apply lids and screw on bands. Process in a boiling water canner for 10 minutes. Eat on fresh scones and store unopened jars in a cool, dark place.