Slow cooked and slightly caramelized, this sweet and tangy Rhubarb Butter is the perfect spread for toast, biscuits, scones, and more. Made with just three ingredients—rhubarb, sugar, and water—this thick and luscious fruit butter is easy to make and can be stored in the refrigerator for several weeks. Perfect for gifting too! Can be cooked in the slow cooker, Instant Pot, or on the stove.
What You’ll Need
A few important notes on some of the ingredients used in this rhubarb butter recipe:
- Rhubarb: You can use either fresh or frozen rhubarb. If using frozen, no need to defrost; just throw it into the pot and start cookin’. If using fresh rhubarb, make sure to remove any leaves as they are slightly toxic. Usually if buying from a grocery store, the leaves will already have been removed beforehand, but just a warning if you have been gifted rhubarb from a neighbour or picked up some at the farmer’s market. Only the rhubarb stalks—which may be green, white, or scarlet—are edible.
- Sugar: You may use either brown sugar, granulated sugar, coconut sugar, jaggery… even alternatives like stevia, monkfruit, or erythritol! I prefer brown sugar as it’s more affordable than most other options while adding a nice caramelized touch to the rhubarb butter.
- Flavourings: If you want to add spices: I recommend warm spices, like cinnamon, ginger, nutmeg, or cloves. Apple pie spice or pumpkin pie spice fit the bill as well. I wouldn’t add more than 2 tsp of spices total. In fact, I like this rhubarb butter best on its own, with no additional flavourings other than a bit of vanilla extract. I love the smell and taste of rhubarb on its own. The spices change the flavour profile quite a lot and obscure its fresh tartness.
For a full list of ingredients and quantities, refer to the recipe card at the bottom of this post.
Step-by-Step Process
This recipe can be made in the Crock-Pot, Instant Pot, or on the stove.
Step 1: Chop rhubarb into pieces and add to a slow cooker, Instant Pot, or Dutch oven.
Step 2: Pour in the water.
Step 3: Add sugar. No need to stir it in.
Step 4: Cover with lid and cook. Instructions below differ depending on which equipment you’re using:
Instant Pot: Use the Pressure Cook setting for 5 minutes, quick release.
Slow Cooker: Use the High setting for 1 hour.
Stove: Set on high heat and bring to a boil, then turn the heat down to medium-low and simmer for 10 minutes.
Step 5: The rhubarb should now be cooked into a soft pulp. Transfer this to a blender and blend until very smooth. (I used my Blendtec on Smoothie mode.)
Step 6: Pour the blended mixture back into your pot. Do not cover. Cook according to the instructions below. Transfer to jars while still warm, then let cool to room temperature.
Instant Pot: Use the Slow Cook setting on Low mode for 6 hours. Stir every 30 minutes, scraping the bottom to prevent sticking.
Slow Cooker: Leave it on the Low setting for 6 hours. Stir every 45 minutes, scraping the bottom to prevent sticking.
Stove: Use the lowest heat setting and cook for 3 hours. Stir every 15 minutes, scraping the bottom to prevent sticking.
How to Use Rhubarb Butter
Since making my jar of slow cooker rhubarb butter, I’ve been experimenting with them in a bunch of different applications. Of course, there’s the classic slather-on-toast but that gets old, so I thought up a few other ideas.
Icelandic Rhubarb Squares
Hjónabandssæla is one of the most iconic Icelandic desserts. These sweet and sticky cake squares are traditionally made with rhubarb jam and rolled oats, but you can substitute rhubarb butter for the jam to get a more intensely caramelized rhubarb flavour. Highly recommended!
Peanut Butter & Jelly Sandwiches
I have not eaten a PB&J in years. YEARS!
So when I baked my weekly batch of bread (it was an Anadama loaf, recipe courtesy of King Arthur Flour, but you can also use my Sandwich Bread), I prepped a bunch of mini peanut butter jelly sandwiches. Well… I ate three on the spot because, like I said, it’s been yeeears.
I wrapped each one tightly in plastic wrap, then put all of them in a big freezer bag. A week later I took one out and popped it in the toaster oven, and it still tasted great! Makes a great lil snack for times when I feel a bit hungry but don’t want to bother dirtying dishes to make something on the spot.
Vegan Double Rhubarb Loaf
I’m not sure whether to call this a bread or a cake, it’s somewhere in between. It’s sweet enough to be enjoyed on its own, but not so decadent that you get sick of it after two bites. Recipe here: Double Rhubarb Dream Loaf
The batter incorporates both fresh rhubarb and rhubarb butter, and there’s also a thread of rhubarb butter running through the middle to give it a swirl look.
Rhubarb Haupia
A new way to use up rhubarb butter that I’ve just discovered is to warm it up and smear it over a square of Haupia Pudding. The tanginess of the rhubarb is a perfect contrast to the sweet and rich coconut pudding.
Please comment if you have another yummy way to use up rhubarb butter. I still have almost a cup of the stuff left!
Recipe FAQs
Fruit butter has a smooth and spreadable consistency that is thicker than jam. However, it doesn’t solidify into a jiggly block like jelly does. The texture of this rhubarb butter is smooth and velvety, highly spreadable, with a concentrated tangy rhubarb flavor.
There are several ways to preserve rhubarb so that you can enjoy it throughout the year. Here are a few methods for preserving rhubarb:
1) Freezing: Rhubarb can be frozen for up to 12 months. Simply wash the stalks, cut them into pieces, and store them in an airtight container or plastic bag in the freezer.
2) Canning: Rhubarb can be canned as a jam or compote. Follow proper rhubarb canning procedures to ensure safe preservation.
3) Dehydrating: Rhubarb can be dehydrated in a dehydrator or in the oven at a low temperature until it is dry and brittle. Store the dried rhubarb in an airtight container.
4) Rhubarb butter: Make this rhubarb butter recipe and it will last in the fridge for up to one month, without requiring any canning. The sugar in the recipe acts as a natural preservative.
Generally it’s recommended to chop rhubarb into small pieces before freezing to make it easier to use in recipes, because thawed rhubarb is mushy and more difficult to cut. (For example, this rhubarb loaf cake uses diced rhubarb.) But for this recipe, you’ll be blending everything up anyway so you can definitely freeze rhubarb in long stalks without cutting them up first.
Recipe Card
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Slow Cooker Rhubarb Butter
Use Imperial/Metric buttons below to toggle between volume vs weight measurements. I recommend weighing out your ingredients for best results.
Ingredients
- 1 ½ lb chopped rhubarb
- 1 cup brown sugar
- ¼ cup water
- 2 tsp vanilla extract *optional
- other spices as desired *optional; see Note 1
Instructions
- Add all ingredients into the slow cooker. (You can also cook this recipe using the Instant Pot or stove; see Note 1.)
- Cover and leave on HIGH for 1 hour.
- Transfer contents to a blender and blend until very smooth. (I use my Blendtec on Smoothie mode, which is perfect for this.)
- Pour blended mixture back into slow cooker.
- Leave on LOW for 6 hours. Do not cover.
- When desired consistency is reached, stir the mixture well before pouring into jar for storage.
Notes
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Here are the instructions for Instant Pot or stovetop:
- Instant Pot: Add all the ingredients to the Instant Pot. Use the Pressure Cook setting for 5 minutes on High mode, then quick release. Transfer to a blender and blend until smooth, then pour it back into the Instant Pot. Use the Slow Cook setting on Low mode for 6 hour with the lid off, stirring every half-hour.
- Stove: Add all the ingredients to a heavy-bottomed pot, like a Dutch oven. Cover and bring to a boil, then reduce the heat to medium-low and simmer for 10 minutes. Transfer to a blender and blend until smooth, then pour it back into the pot. Using the lowest heat setting, cook for 3 hours, stirring every 15 minutes.
- If you want to add spices: I recommend warm spices, like cinnamon, ginger, nutmeg, or cloves. Apple pie spice or pumpkin pie spice fit the bill as well. I wouldn’t add more than 2 tsp of spices total. In fact, I like this rhubarb butter best on its own, with no additional flavourings. I love the smell and taste of rhubarb on its own. The spices change the flavour profile quite a lot and kinda obscure its fresh tartness.
Can I freeze this
Hey Nadine, I haven’t tried freezing this particular recipe before. Although, I have frozen apple butter before with good results so I think rhubarb butter should be safe to freeze since it has a similar composition.
thank you from Vancouver Island, BC, Canada : )
If I double or triple this, should I follow the same cook times?
It will take a bit longer for bigger batches. I would expect the cook time to increase by about an hour if doubling the recipe. Note that you could reduce the cooking time if you use a larger-bottomed pot (more surface area of the mixture exposed = quicker evaporation)
Thank you! ❤
I’m not usually a fan of rhubarb, but this recipe won me over! I added 2 teaspoons apple pie spice and it smells like a cozy candle. Except i can actually eat it!!!
Lol I completely get what you mean, some of those scented candles are definitely forbidden snaccs 😆
I have never tried rhubarb butter before but you certainly have given me something to look forward to trying out. Thanks for sharing this week at #HomeMattersParty
Rhubarb butter…yum! Definitely want to try this. Thanks for sharing! Visiting from the #homemattersparty today. Have a great weekend!
Thanks Marielle, hope you give it a go!