Slow Cooker Caramelized Onions
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Slow Cooker Caramelized Onions are the best kitchen shortcut! No more babysitting a skillet on the stove forever, your arm hurting from all the stirring. You can caramelize onions in the crock pot with a little butter and salt while you go about your day. They’re the perfect topping for sandwiches, burgers, and so much more!
Slow Cooker Caramelized Onions
I don’t know about you but I love love love onions!!! Roasted, fried, in salads and soups, there’s no wrong way to eat them.
And much like butter, caramelizing makes everything better.
To use up the last of the crate I got from a friend, I made a big batch of slow cooker caramelized onions… and then finished them off myself in about 2 weeks…
Toast, sausage, hamburgers, burritos with chicken, burritos with cheese, burritos with just the onions — you get the idea!
I tried two different ways to caramelize onions in the crock pot, and just a minor change made a HUGE difference.
The first batch included just 1 tablespoon of sugar to get things going, and they were almost sickly sweet. The second (without sugar) came out perfect!
Ingredient Notes and Substitutions
- Onions – Any yellow onion is perfect for this caramelized onions slow cooker recipe, but it will work with white or red onions too.
You could even use a mixture to create more depth of flavor! - Butter – Use unsalted so you can control how much actual salt goes into the pot. And no margarine here, only real butter! You can use olive oil or a combination of both.
- Salt – This helps draw out the liquid from the onion slices and dissolve the natural sugars. Don’t skip it!
Tips and Tricks to Caramelize Onions in a Slow Cooker
- Make adjustments depending on the size of your crockpot.
The larger your crockpot, the more you’ll be able to add from the start.
When I used my 5 quart, I was only able to fit about three-quarters of my onion slices at first, but was able to add more as they started to reduce. When I use my 6-quart they fit perfectly.
It will take a few hours of cooking before they soften and reduce enough to add more, but it takes the full 8-10 hours to caramelize onion in a slow cooker.
- Stir occasionally to prevent sticking.
While this method is far more hands-off than the stovetop method, it still requires a little attention.
Stir caramelized onions in the crockpot every 2-4 hours or so to ensure they don’t stick to the bottom or sides — and so they brown evenly. Cooking on low you shouldn’t have any issues this way.
Cooking time will also vary based on the size of your crockpot and how much natural sugar is in your onions.
Prep Ahead
- Slice onions
Kitchen Tools You Will Need
- Slow Cooker – Great for soups, roasts, shredded chicken, and more! I love it in the cooler months, but it’s also great in the summer when you don’t want to heat up the whole house with the oven.
- Quality Knives and a big solid Cutting Board make prepping a breeze and are well worth the investment.
- Heat-Resistant Spoon or Spatula – Perfect for stirring and serving caramelized onion slow cooker style.
Serving Suggestions
The correct question is what can’t you put caramelized onions on?!
Have them ready for burgers, hot dogs, steak, chicken… anything you’d throw on the grill.
You can also use them to make homemade onion dip or mix into your favorite pasta dish. They’re especially yummy as a pizza topping!
Storing and Reheating Caramelized Onions from the Slow Cooker
Cool to room temperature, then transfer slow cooker caramelized onions to a jar or airtight container.
They will keep in the refrigerator for about a week, though I’ve stretched mine a few days past that before.
These also freeze beautifully! Once thawed, the texture is just like when they were first cooked.
It’s best to portion them into small freezer-safe baggies so you can thaw just what you need. Freeze for 3 months and thaw in the refrigerator.
Reheat caramelized onions on the stovetop over low heat for best results — no need for extra oil or butter!
Caramelized Onions in Crock Pot FAQ
Using 8 large onions, you can make about 4 cups of caramelized onions in the crock pot.
Give your onions a taste when they’re just about done and see what you think.
If they need a little more sweetness, stir in some brown sugar (just a pinch!). If there’s not enough acidity, balsamic vinegar is a great choice.
Saved from our original post of this recipe in 2011:
Today is actually my Mommy’s birthday, and since we can’t be together I am hosting a virtual birthday party. I love you Mommy!
Happy Birthday and I wish I could be with you in person today. You are a gift to our family and everyone who knows you – you have touched so many lives!
We love you and count you as a blessing every day. Thank you for helping me become the woman, wife and mother I am today! Have a beautiful Birthday! XOXO
Enjoy!
With love, from our simple kitchen to yours.
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Slow Cooker Caramelized Onions
Equipment
Ingredients
- 4 tablespoons unsalted butter, melted (or olive oil)
- 1 teaspoon salt
- 8 large onions, halved and then sliced ⅛” – ¼” thick (about 3-4 pounds)
Instructions
- Add onions to a 6 quart slow cooker. Pour the butter (or oil) over the onions and sprinkle with the salt. Stir to combine.
- Cook on low 8-10 hours, stirring occasionally (every 2-4 hours). Caramelized onions will be a rich golden brown color.
- Remove the onions once they are caramelized to your preferred taste, remove from the crock pot. If they start burning and become incredibly aromatic, be sure to check them. Enjoy, they are so incredibly delicious. I am going to make another batch. Each batch makes approximately a pint of caramelized onions.
Donna’s Notes
1. Portioning: Divide the caramelized onions into smaller portions before freezing. Ice cube trays or muffin tins work well for this. Once frozen, transfer the portions to a freezer-safe bag or container. 2. Freezing: Place the portions in a single layer on a baking sheet and freeze until solid. Then, transfer them to a labeled freezer-safe bag or container. They can be frozen for up to 3 months. 3. Thawing: To use frozen caramelized onions, thaw them in the refrigerator overnight or reheat them directly from frozen in a pan over low heat.
Nutrition
All nutritional information is based on third party calculations and is only an estimate. Each recipe’s nutritional value will vary depending on the ingredients used, measuring methods, and portion sizes.
Originally Published September 2011, updated and republished May 2024
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What a lovely idea! Happy Birthday Mommy! These onions look the best! and brilliantly helpful as they add a yum factor to just about anything!
Mary
Sometimes, I just to want to take the time to make carmelized onions. A great solution to having them on hand.
It makes me grin that you are loving them as much as I do!
I bookmarked these on Mary's site and now seeing them again here makes me want to run out and get some onions. I am making these as soon as I get back from the store. I think its very interesting that you cook these with the cover off. Isn't it funny how a little bit of sugar makes onions sweet so quickly?
Happy Birthday, Mom!
Donna, these look just as delicious as they did on Mary's. I think it's a sign I'm supposed to get that crock pot out!
I so need to make these! I love love love caramelized onions but they definitely take a ton of time over a hot stove…this seems like the perfect solution to that! 🙂
i see that you have the onions shown in a mason jar–did you choose it simply for storage or did you have aspirations of preserving the onions for a later time?/is that possible?
Its been a while since I had last tasted caramelized onions and I hadnt thought of it either. I am going to try that out 2morrow.
thx for sharing!
OMG. Brilliant. So obvious and yet never thought of it. Thank!!!
I am so doing this today!!
Do you need more onions? I can have Miles take more to Mary's for you 🙂 I have plenty!!
No where in this recipe,do you state that they need to be cooked on low or high setting. Which is it?
Yum Yum, I am in a crock pot mood and this will fit the bill nicely, I agree about omitting the sugar, what is it with people plonking heaps of white sugar into everything! I love the taste of onions! Thank you.. celi
If you put them in a mason jar, how long do you thing they will keep in the frig?
I just did this last night – on low all night long. I didn't salt them, and only used a couple tablespoons of olive oil. I will try it next time with a bit of butter – but they are fabulous with just the olive oil. made a nice big batch to bring to a cookout and they were a big hit. Will do this on a regular basis!
Did you cook without the lid on?
How long will these keep? Silly question, I know, judging from how delicious they look…
I really don't know for sure. Mine are always devoured quickly. I would say that 2 weeks is about right though. Hope that helps!
Donna
Do you cook them on low or high setting?
Thanks in advance,
Ruth
Hi Ruth! Cook them on high, but be sure to stir them every once in a while (every hour or two).
Hope that helps!
XOXO
Donna
carimal is made with sugar…….maybe vidalia onions.?….please reply as i have 25 lbs. of these sweet onoins.:)
The onions will become sweet without sugar. Trust me. If you add sugar, they will become more a dessert spread. That was with regular yellow onions, vidalia would be great too.
Hope that helps.
XOXO
Donna
In the photo you show it in a canning jar… just for the 'cute' effect or did you can them? If so, what was the process?
They look super yummy and I'd like to can them if possible.
Thanks,
Jean Smith
http://www.fordragonfliesandme.wordpress.com
Hi Jean!
Thanks for taking the time to leave a comment. I did not can these. It is my experience that it is not a good idea to can butter and these are made with butter. I would check with someone who is more of an authority on canning (I am not). I love canning jars and store condiments and such in the fridge in canning jars.
Hope that helps!
XOXO
Donna
Put in freezer containers and freeze. I often do that with onions and mushrooms as I like them on steak and burgers.
I had two crockpots. I cut up three bags of onions. Turned them on at 11:00AM and by 11:30PM they still weren't caramelized. I threw them in the fridge and the next day I finished them on the stove in batches. I'm thinking it might of took so long because I did so many. The final result was delicious though.
That is awesome! I should fill all my crockpots and make more.
I see that you said these would probably last about 2 weeks, I'm assuming that they would have to be refrigerated, since they have butter in them. Is that true?
Absolutely. I refrigerate these for up to 2 weeks. Enjoy!
so it should be uncovered the whoe time?
SO EASY and delicious. What a time saver!
I love how simple and hands-off this recipe is! The caramelized onions are a game-changer for my sandwiches.
Hi Amelia!
We’re so glad you enjoyed.
TSRI Team Member,
Devlyn