For most of the last three weeks, my left crisper drawer has been almost entirely occupied by plums. I’ve slowly working my way through this bounty, cooking them into jam, using them in my various demonstrations, and relying on my slow cooker to turn them into butter (two batches, thus far). The bottom of the drawer is finally in sight and I think the remaining plums will become a batch of cardamom-spiked jam.
I’ve written a great deal over the years about using a slow cooker to make fruit butters, so if you’re a long-time reader, this post might feel oddly familiar. However, I’m of the belief that anything useful and good can always bear repeating, and so, I push on and offer you another slow cooker.
The plums I most like to use for butter are late season Italian plums. Bred for cooking and drying (they are also known as Italian prunes), they are typically the last variety of stonefruit available before the weather slips into fall. They can be slightly bitter or tannic when eaten raw, but once heated or dried, trade those unpleasant elements for a lush texture and natural sweetness.
To make plum butter, I fill my biggest colander, give the plums a good rinse, and then stand at the sink for a time to cut the fruit into halves and remove the pits. I find that for my 6 quart slow cooker, my starting weight is typically between 7 and 8 pounds.
Then I heap those plum halves in the cooker, add a few tablespoons of water to prevent scorching in the early stages of cooking, set the lid in place, and cook on high for somewhere between 2 and 4 hours. This first stage of cooking is designed to soften the plums enough so that they can easily be pureed with an immersion blender.
Once they’re soft, I apply my immersion blender until the plums have been transformed into a puree. Then I balance a wooden chopstick across the lip of the slow cooker crock, and rest the lid on top of it, so that the steam can easily vent. Finally, I turn the cooker on low and proceed to cook the plum puree down over the course of the next 6 to 10 hours (your mileage will always vary here).
I try to give the cooking butter a good stir every couple of hours, to ensure that the top doesn’t dry out while the underside burns.
Once the plum puree has reduced down to a dense, thick, spreadable butter, it is done. I like to scrape it out into a medium saucepan for the final pureeing, because if you’ve done your work well, there won’t be enough depth in the slow cooker for an immersion blender to work well.
When the butter is smooth from the second application of the immersion blender, I put it on the stove over low heat, and add the sweetener and spices. Stir constantly, until the butter is hot and the sweetener is fully combined. In the case of this batch, I sweetened with brown sugar, thinking that it’s molasses-y flavor would go well with the plums. I also added 1 teaspoon of cinnamon, 1/2 teaspoon of ground nutmeg, and a splash of lemon juice for balance.
As with all fruit butters, you can sweeten this one to your taste. You could reduce the amount of sugar, use regular granulated sugar, add a bit of honey instead, or even leave it entirely unsweetened (though I find that even a small amount of sugar helps balance the fruit and also improves shelf life).
To preserve, funnel the finished butter into jars (I like half pints for this one, as a little goes a long way), leaving a generous 1/2 inch of headspace. Wipe the rims, apply the lids and rings, and process in boiling water bath canner for 20 minutes. I always process fruit butters for longer than jam, because their increased density makes it harder for the heat of the canner to penetrate to the center of the jar. A longer processing time helps combat that.
Slow Cooker Brown Sugar Plum Butter
- 7 pounds Italian plums
- 1 cup brown sugar
- 1 teaspoon cinnamon
- 1/2 teaspoon freshly grated nutmeg
- Juice of 1 lemon
- Wash plums, cut them in half, and remove pits.
- Place the plums into the slow cooker. Add 2 tablespoons of water and put the lid on the cooker.
- Set the cooker to high and cook for 2 to 4 hours, until the plums are tender and have released a great deal of liquid.
- Using an immersion blender, puree the fruit until smooth.
- Set a wooden chopstick across the rim of the slow cooker and set the lid on so that it is vented slightly.
- Turn the cooker on to low heat and cook the fruit puree for 6 to 10 hours, until the plum puree has reduced into a thick, dense, spreadable paste.
- Scrape the finished butter into a medium saucepan and puree again with your immersion blender. Place on the stove over low heat and stir.
- Add sugar, spices, and lemon juice. Taste and adjust as necessary. Keep stirring until the butter is hot and the sugar and spices are fully incorporated.
- To process, funnel the finished butter in half pint jars, leaving 1/2 inch headspace.
- Wipe the rims, apply the lids and rings, and process in a boiling water bath canner for 20 minutes.
- When time is up, turn off the heat, remove the lid from the canner, and allow the jars to cool gradually in the water.
- After they've slowly cooled for 6 to 7 minutes, remove the jars from the canner and set them on a folded kitchen towel to cool.
While I vastly prefer water bath canning, my canning stuff is packed to move… Could I freeze this fruit butter? Do you think it would hold up/retain its texture?
I never freeze things that are safe for canning because of my space limitations, but I imagine it would do okay in the freezer.
Me either but… Thanks, I’ll give it a try.
Those plums are just so photogenic! Gorgeous. I love the addition of brown sugar. I have made some plum butter already—I’m thinking of it slathered on cinnamon bread. Now all we need is the cold weather!
Question. What would be the difference. Pressure canning butters, jams and Kelly’s as opposed to water bath?
My understanding is that the higher temp in a pressure canner would break down the pectin. However, you can use a pressure canner for water bath by not sealing the canner.
Oh, yum! This looks SO good. I didn’t get any plums off of my tree this year due to a late frost… but I am defiantly going to have to pin this for next year!! Thank you!!
With the onset of Fall im beginning to get squash from my CSA. I ran across Fruits of the Earth, by Gloria Nicol which has a beautiful recipie for Pumpkin Vanilla jam. This jam ends up in a hot water bath and I was wondering (if I follow the recipie exactly) will it be safe and shelf stable?
Beware of pumpkin as a home canner – as I discovered it is not possible to safely water bath can pumpkin at home. When I was just starting out with canning I tried to make some beautiful pumpkin butter and all of the jars started bubbling over with yucky stuff and leaking everywhere. My husband still jokes about the time I tried to kill him with pumpkin…
I never do pumpkin products in a boiling water bath canner.
Pumpkin butter was tested & found not safe–low acid and too dense. It freezes really well, though. Or, you can pressure can cubes of pumpkin and make butter later. Same with dehydrated pumpkin…
oooh, this looks luscious! I bet I can still get Italian plums at market. I’ve been making Marian Burros’ Famous Plum Cake with them. And I totally agree about the slow cooker for cooking things down. It’s amazing.
So could you combine your cardomon spiked plum jam with this plum butter? Replace cinnamon with cardamom? Or doesn’t brown sugar go with cardomon?
This looks great, but I am worried without sufficient sugar that the butter will not be safe. I thought it was the fruit sugar/ratio that preserved the butter?
Could I do this with other fruits?
My understanding is that sugar preserves color and extends shelf life but isn’t necessary for safety. (Think low-sugar pectin). Personally, I would double the sugar for this batch as my family likes a sweeter product and I’d use within 6-9 months.
Oh, this looks good.
A question: I’ve been making your oven-roasted spiced plum butter for several years now, and I love it. That recipes says to process for 10 minutes, though – should I be doing it for 20 instead?
That oven roasted plum butter is far less dense than this one, so ten minutes it still fine for it.
I miss my plum tree.
I learned to can just this summer and made jam with just about every fruit and berry as its season arrived. The Italian plum jam was one of the standouts, and I made so much (in addition to freezing halved plums and making at least five of the famous NYT plum torte) that I swore I was done with the plums. AND NOW YOU SHOW ME THIS.
I’ve got a batch of this in the canner now but wonder if I made a mistake. I started with about 4.5 pounds of plums and ended up with a bit over three cups when it was cooked down, but when I gave it the final puree with the immersion blender the volume increased to a bit over 3.5 cups. I assume some air got incorporated? Is this going to be a problem with the finished product? I did check for air bubbles and didn’t see any, it’s just a greater volume overall.
(Since I had more than I expected I tucked the extra into 4 oz jars and am processing them with the half-pints for the full 20 minutes).
I’ve never measured the fruit butter before pureeing, so I’m not entirely sure what it does to the finished volume, but I would not worry about it.
On the whole we don’t do ‘canning’ on this side of the pond – but I can understand that using a water bath is important. Fascinated by the idea of using a slow cooker for making butters and I think I will give it a go.
Louise in Somerset, England
Amazing thing. I just made this, but I didn’t have enough plums to warrant using my slow cooker. So, what other appliances do I have that keep food cooking low, for long periods of time, and are vented? Answer: my rice cooker!!!
It worked so well, i can’t even convey my glee. after the initial cooking period, the plums were already that lovely soft texture, the skins were shredding. I transferred the plums to another container to puree with my immersion blender, seasoned, and popped them back in the rice cooker to thicken up just a tiny bit more. I ended up with about 20 oz of plum butter, and am so pleased about my short-cut that i’ve been squealing all day!
What a smart thing to try!
Awesome. Would you mind sharing the brand of slow cooker you use? I’m in the market for one. Thank you in advance
I use a Hamilton Beach Set n’ Forget slow cooker. I wrote a little about it here: https://foodinjars.com/2012/12/spiced-apple-butter-giveaway/
Looks delish! Thanks for the recipe, I featured it on my blog: http://www.colorfulcanary.com/2015/10/16-not-so-pruney-ways-to-preserve-plums.html
Any tips/is it possible to make this without a slow cooker, in a regular pot? I don’t have a slow cooker but I do have quite a lot of italian plums at the moment! Help!
I would like to double this recipe because I want to do this with all my plums and don’t want to have to do the long cooking time over and over. Do I need to adjust how long I cook it?
When you increase the amount of volume in the pot, the cooking time is always going to be longer. How much longer, I can’t really say. You’re just going to have to cook it until it is done.
Thanks but I grossly over estimated the amount of plums we have lol. I did however have plenty for the single batch. My question now is it has a tartness is that normal? Also does it thicken as it cools?
I have a question….on the slow cooker, brown sugar butter, could you add jalapenos, after pureeing them, what do you think? thank you
I wouldn’t do it. If you want to integrate heat into this preserve, try using a dried spice like red chili flakes rather than a fresh pepper. Dried spices don’t impact the finished acid levels as negatively as fresh ingredients do.
I made this and gave up. After more than 36 hours in the slow cooker, it was still super thin like applesauce. I decided to switch it up and make fruit leathers with it instead.
Our Italian plum tree EXPLODED this year, and I just made a double batch of this. It’s perfectly sweet and plummy! Thank you for sharing!
So glad you like it!
I added the brown sugar to the slow cooker by accident. Will this be okay that it cooks the entire time with the plums?
Adding the sugar to the plums increases the chance that it will burn during the cooking process. Make sure to watch it more carefully.
Hi I am hoping to make this and not do the hot water bath (since it’s going to be 90*+ for weeks. Can I freeze it? How long would it keep in the fridge? I don’t have an immersion blender either, so I’d be removing it and using my food processor.
You can freeze it, but you want to leave extra headspace to account for expansion. And it will only keep a handful of weeks in the fridge. It’s a relatively low sugar preserve.
You can certainly freeze it. It will only keep for a couple weeks in the fridge.
Wow, thank you thank you! I planted an Italian Plum 12 years ago and have hated eating the fruit and wondered why I planted it. This year I found this recipe and tried making this plum butter with all those plums that never “ripen”….I’ve made two batches and it’s delicious. Now I love my tree!
I’m so glad I’ve helped you love your tree!
Hello, can you please explain why we need to transfer the butter to a medium saucepan for the second immersion blending? Why can’t we leave it in the slow cooker? Too shallow? Thank you!
There is typically too little in the slow cooker to puree well. I also realize that I left a step out, and that is that I put the butter back on the heat once it is in the saucepan, to help the sugar dissolve into the butter. I will correct that right now.