I’ve made blueberry butter to go in the holiday teacher gift boxes for Hannah’s school a couple of years running now, and once or twice in between. Sometimes I throw in some maple syrup, sometimes I make it with lower sugar, but this is the general recipe I like to use, from Chowhound. It’s pure essence of blueberry, and smeared on a piece of buttery toast it’s like nirvana. These ingredients make about 3 pints, or 6 little half pints (I like the small jars for gifts).
8 cups of pureed blueberries
2 cups sugar
1 lemon, zested
2 teaspoons cinnamon
1/2 teaspoon grated nutmeg
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. Once it’s hit 4 hours in the slow cooker, check to see if it’s thickened to a consistency almost like thick applesauce. Add the sugar and spices, and cook it for another 1-4 hours until it’s thick and spreadable. The original recipe says put the spices and the sugar in for the last hour, but that’s hard to predict.
My first batch of blueberry butter spent about six hours in the slow cooker before I canned and processed it. 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. The last batch I made, this past December, I left it overnight for about 7 hours on low, then added the sugar and spices for another hour when I woke up in the morning. I left the lid on the whole time, it was yummy.
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.