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Slow Cooker Caramelized Onions

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Slow Cooker Caramelized Onions -- a quick and easy tutorial | gimmesomeoven.com

Earlier this week, I shared with you my tutorial on how to make caramelized onions the traditional way. On the stove. Low and slow. With 40 minutes of basically constant stirring. It’s the way that people have been making caramelized onions forever and ever, and with good reason. The technique will yield you some crazy delicious onions.

But.

Awhile back, I heard a little “rumor” (ok, I saw something on Pinterest) about the possibility of making caramelized onions in the slow cooker, and I immediately had to investigate. The idea seemed too simple. Just throw onions and butter in the slow cooker and let them cook for hours and hours and hours, without having to babysit the crock pot and stir them every few minutes, and go through the process of deglazing the pan?!? Nope, I figured there was no way it could work, or that those onions would have the same delicious flavor of their stovetop counterparts. No way.

But I’m here to tell you today — yes way.

My brilliant slow cooker once again proved to me that it can do just about anything. And I have been making batch after batch of heavenly slow cooker caramelized onions ever since. And if you love caramelized onions, you absolutely need to try this too.

Caramelized Onions | gimmesomeoven.com

First off, I will still always be a fan of the traditional stovetop method for making caramelized onions. And if you’ve never tried making them yourself, I highly recommend adding this method to your skill set.

However.

It’s no secret that I’m all for any shortcuts that fall in the “quick and easy” category with cooking. And once I learned how unbelievably low-maintenance and easy the slow cooker method was, and how ridiculously delicious the onions would turn out, you’d better believe I became an instant fan.

Slow Cooker Caramelized Onions -- a quick and easy tutorial | gimmesomeoven.com

And I’m here to tell you — it literally couldn’t be easier.

Just slice up a bunch of onions. (You can use white, yellow, or red onions, or a combination of any of those.)  Toss them with some melted butter. Then let them cook on low for about 12 hours total until they reach that perfectly caramelized, deep golden brown, sweet and savory perfection.

Yep. It really is that easy.

Slow Cooker Caramelized Onions -- a quick and easy tutorial | gimmesomeoven.com

A few tips though:

Lid Ajar: The onions will definitely release lots of natural juices while cooking, which can make the onions slightly soupy near the end. So if you would like that liquid to evaporate, thus making your onions a little thicker and “jammier”, just set the slow cooker lid slightly ajar (1-inch of so) for the final few hours of cooking.

Balsamic and Brown Sugar: I happen to fall in the camp of believing that caramelized onions are plenty flavorful on their own. But if you taste them in the final few hours and decide that they need some extra flavor, just stir in some balsamic vinegar and brown sugar to taste. They will provide the extra savory and sweetness that many people love.

Know Your Slow Cooker: These onions should be able to cook unattended for 10+ hours without any babysitting or stirring. (Although I do recommend stirring them once or twice if you can.)  But that said, every slow cooker is different. And the low heat setting on yours could be hotter than most. So, as is good common sense with any slow cooking, I just recommend keeping watch especially during your first batch to be sure that the onions do not burn on the bottom.

Slow Cooker Caramelized Onions -- a quick and easy tutorial | gimmesomeoven.com

 

So are you ready to give these a try??

I seriously hope you do…and then report back with how they turn out. Enjoy!!Slow Cooker Caramelized Onions -- a quick and easy tutorial | gimmesomeoven.com

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Slow Cooker Caramelized Onions

5 Stars 4 Stars 3 Stars 2 Stars 1 Star 4.9 from 14 reviews
  • Prep Time: 10 minutes
  • Cook Time: 720 minutes
  • Total Time: 730 minutes
  • Yield: 0 About 3 cups 1x

Description

These slow cooker caramelized onions are unbelievably easy to make, and only require 2 main ingredients!


Ingredients

Scale
  • 34 pounds white, yellow or red onions, peeled and thinly sliced
  • 3 tablespoons butter (or olive oil), melted
  • salt and pepper
  • optional: 1 tablespoon of brown sugar and 2 teaspoons of balsamic vinegar

Instructions

  1. Add onions to the bowl of your slow cooker.  Drizzle the melted butter evenly over the top of them, then toss with a spoon (or with your hands) until the onions are evenly coated in the butter.
  2. Cook on low for 8-10 hours, stirring once or twice if desired, until the onions are a rich golden brown and caramelized.  Season with salt and pepper (and brown sugar and/or balsamic, if desired), and stir to combine.
  3. If your onions are really juicy at this point, set the lid an inch or so ajar.  If they are not, leave the lid on regularly to seal in the moisture.  Then continue cooking the onions for an additional 3-4 hours until most of the extra liquid has evaporated and the onions are a deep golden brown, and thick and “jammy”.
  4. Serve the onions immediately, or cover and refrigerate for up to 3 days.  Or freeze for up to 3 months.

Notes

Lid Ajar: The onions will definitely release lots of natural juices while cooking, which can make the onions slightly soupy near the end.  So if you would like that liquid to evaporate, thus making your onions a little thicker and “jammier”, just set the slow cooker lid slightly ajar (1-inch of so) for the final few hours of cooking.

Balsamic and Brown Sugar: I happen to fall in the camp of believing that caramelized onions are plenty flavorful on their own.  But if you taste them in the final few hours and decide that they need some extra flavor, just stir in some balsamic vinegar and brown sugar to taste.  They will provide the extra savory and sweetness that many people love.

Know Your Slow Cooker: These onions should be able to cook unattended for 10+ hours without any babysitting or stirring.  (Although I do recommend stirring them once or twice if you can.)  But that said, every slow cooker is different.  And the low heat setting on yours could be hotter than most.  So, as is good common sense with any slow cooking, I just recommend keeping watch especially during your first batch to be sure that the onions do not burn on the bottom.

Slow Cooker Caramelized Onions -- super easy to make with just 2 ingredients! | gimmesomeoven.com

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55 comments on “Slow Cooker Caramelized Onions”

  1. I am obsessed with caramelized onions! Loving the slow cooker shortcut! Can’t wait to try it! 

  2. I can’t wait to try these! You are my favorite food blogger – every single recipe of yours I’ve tried has become an instant hit. Slowly I’ve been transitioning my “go to” recipes to all be yours. Thank you, thank you!!!

  3. These look really good! That slow cooker…she’s a must have isn’t she? 
    https://absolutelytara.com

    • Excellent recipe! And if you want French Onion Soup, just at some sprigs of thyme to the crockpot, remove them after cooking and add beef broth to the onions. Delicious!!






    • Love, love love this, just wish you could get rid of the adds that separate the recipe. Can’t make a single screen shot for viewing later .

  4. Brilliant — when you mentioned making the onions ‘jammier’ it made me think that you could make a great onion jam like this too!

  5. This is genius! I love caramelized onions but I’m usually too busy (cough lazy) to see a pan all the way through. Pinning so I can give the slow cooker method a try :)

  6. This is amazing! I am such a lover of caramelized onions but I honesty despise the process. I love that you could make a gigantic batch of these and then save them in the fridge or freezer :)

  7. Now this is a good reason to plug in my slow cooker! So smart. 

  8. It looks amazzzingggggg! So delicious! Need to try this recipe.

    www.trangscorner.com

  9.  I do them this way and then freeze in small portions in a silicone muffin tin.  When they’re all frozen I pop them out of the muffin pan and into a ziplock.  Makes it soooo easy to quick defrost some to throw on a burger or sandwich.   Yum!!

  10. Ali,
    This is so wonderful.  I love caramelized onions and this recipe means I’ll have them more often.  Thanks!  Todah!  Merci! Gracias! Tak! Spasibo!
    Marnie

  11. Second time I’ve tried this. After an hour, there’s a faint vinegar smell to the the onions.  I didn’t add vinegar or anything, just olive oil.  Is this very unusual?  Maybe it was a bad onion?  Has this happened to you?  

  12. Hi! Saw this come through on my Pinterest, and thought I’d leave a comment. I have been making my carmelized onions this way for decades. Heck, I thought I invented it! I never melt the butter separately,  and I use a whole stick. I put the butter in the warming crock while I slice up my onions. Then I shove as many onions as I can in there, and often, the lid isn’t even sitting on right. As you said, they cook down. I use sweet onions and buy at least 10lbs at a time when they’re in season. By using sweet onions (Walla Walla, Vidalia or the like) you will not need the balsamic and brown sugar. If they don’t all fit at once, I just wait and add the rest as they cook down. Then I have a pot full of mahogany onion goodness. Then once cooled, I put it in 1 cup plastic containers, and freeze them. I use these to top pizza, baked potatoes or hot grilled meats. I also use this to quick start risotto, or make a small batch of quick French onion soup. It’s one of my favorite kitchen staples! 

  13. I made your caramelized onions yesterday for my onion soup.  I had never done this before and my onion soup was the best ever! 

    Thanks so much, 
    Debbie

  14. Definitely going to try this.  I make approximately 125 lbs of potato filling for pierogiss. And the most time consuming for me is carmelizing  thr onions.   My husband does all thr peeling. I mash and put filling together. This will be awesome. 

  15. Can these be frozen?

  16. Can the process be accelerated by putting on high for a few hours at the beginning?
    Don’t really have 12 hours to make these.

    • Hi Karen! Hmmm, we’d be afraid the onions would burn. If time is an issue, we suggest you don’t do the slow cooker version — you can’t go wrong with this classic method!

    • Probably, IF you add additional liquid, that will keep them loose, and movable (soupy) as they cook on high, which will steam off as they cook down, and disappear as they cook on low. Also, if you do try to cook them on high, you might have to babysit them more, and stir them more, to prevent burning.Maybe 3 hours on high, then 3 hours on low would work?

  17. So much Yim and so easy!  
    I like adding fresh thyme to my carmelized onions. 
    Thanks for the recipe! 

  18. Hi, just wanted to know if this can be canned

    • Hi Lilly — good question! We’ve never tried canning these, but apparently you can: We hope this helps!

  19. Once my onions had cooled they had solidified butter on them. Did I use too much butter?

  20. Accidentally left them cooking (on low) on the patio for 24 hours. For real! Turned out terrific!






  21. Maybe you could shorten the slow cooker time, by pan sauteing the onions, on a stove top, with the pan covered, with with some water, or broth in the pan, to keep them hydrated. Then, when they cook down, and are limp, then transfer to the slow cooker, checking, stirring & adding water, until they’re done. Maybe also, microwave in water or broth, until limp, then transfer to the crockpot. I think it’s worth trying, to cut the cooking time down to a more reasonable time.

  22. Easiest way ever to caramelize onions. I had some very large onions that I needed to use up (not always easy when you’re cooking for one). I used a combination of red, yellow and white onions, combined EVOO and butter and set it and forgot it (not really, stirred a couple of times). I did turn the lid for a bit to cook down some extra liquid, but the end result was delish.






  23. I recently got a small slow cooker (1.5 litres) and my first effort (rice) was a total fiasco. But THIS recipe for caramelized onions was a triumph! I’ve made them regularly on the stove top, but what a hassle and I don’t think I ever got the caramelizing quite right – had to add sugar and balsamic vinegar. Did this pinnacle of yumminess in the slow cooker, just with butter and a bit of olive oil for luck, and it turned out better than anything I’ve done before. No other additions. The learning curve – they really do cook down to very little, so next time I’ll double up on the onions (I only used 5 medium/large onions, in expectation of failure). Just the most delicious thing I’ve eaten for ages. Thanks for the spot-on guidance – it took 10 hours on low, as you say. A stir every hour or so. Much better than on the hob and 1/10 of the effort. Thank you!

  24. I eat a ton of carmelized onions so I had hoped this recipe would allow me to make a much larger volume so I’m not making a pot full every three days or so. Unfortunately the flavors on these never really developed. I’ve never had to add anything to my onions and I’ve made countless batches and these were comparatively boring despite following the recipe closely. I taste tested them at 10, 12, and 14 hours and they never picked up the rich sweetness I love. They weren’t bad, just not nearly as good. It’s back to the stovetop for me.






  25. I love that there is juice at the bottom. Whatever is there I use a turkey baster and squeeze out the juice into ice cube trays (I bought a couple and keep them just for this purpose). Then I freeze the trays and once frozen pop the cubes into Ziploc bags. Then when I’ making soup or anything I want to add a little extra flavour to I throw one or two cubes into the recipe for a wonderful add on flavour.






  26. I do my onions like this all the tme. They are actually in my crockpot now for french onion soup tomorrow. I drizzle in olive oil instead of butter and add salt and pepper, whole garlic too.






  27. I make a batch of caramelized onions 2 or 3 times a month, although with slight variations. In one batch, I finish the cooking with minced mushrooms and chicken base. This is especially good for use in a matzo brei. Another method is to mix tiny bits of stew meat in, add a bit of semi-dry amontillado the last 10 minutes and finish with beef base. This is nice to put on a crusty slice of bread inside a toaster oven with gruyere/parmesan, which I call onion soup toast. Quite delicious. I’ll have to try out your slow-cooker method and see what happens.

  28. I SOOO used way too much butter…it’s actually pooling in the onions. They’ve been cooking for 9 hours, so I put the lid to the side and am hoping something happens that’s good? Or am I just gonna have super greasy onions and that’s it?






  29. I was sad when the last teaspoon was gone! ??






  30. LOVE LOVE LOVE slow cooker caramelized onions. I make a huge batch (I use my like 8 or 10 qt slow cooker) and then break them up into 1 cup baggies and then freeze. Usually go through at least 1 bag a week. We put them in everything … dips, stir fries, meatloaf, puree and use in wet rubs/marinades. Never tried the sugar/balsamic, but will probably give it a try!






  31. I must have done something wrong. We used the mandolin to slice the onions then tossed with butter, salt and pepper. We use a 5lb bag of white sweet onions and probably a little more than 3 tbs of butter for the extra lb of onions. They started to burn on the sides so stirring to push them down was inevitable. At the end of probably 15 hours of checking the still soupy onions and leaving the lid ajar, they ended up looking burnt on the top and soupy on the bottom. Did I stir it too much? How did it still end up soupy?

    • Probably sliced the onions too thin using the mandolin. Mandolins are very abrasive on onions, breaking all the cell walls, so they probably leaked out all the moisture quickly and burned. When I make this recipe, I rough chop them. Hope this helps!

  32. I found a little trick to prevent stuff from burning in a slow cooker: one, use a slow cooker liner and two put a cup or two of water between the slow cooker and the liner. This prevents hot spots because the water acts as a buffer and spreads the heat out. Plus it makes cleanup simple.
    Loved the recipe, helps when making large batches of Onion dip.






  33. What do I do with this many onions?

  34. I made these in my crockpot and they were perfect. Tank yo so mu cof the easy and delicious recipe!!

  35. This concept is an awesome new discovery for me! With ADD, any distraction can pull me away from the stove and I end up burning things, so, this might be a game-changer for me. :)

  36. Just add broth after the onions have been simmering for 8 hours and you make the easiest onion soup ever.

  37. I’ve coked onions this way for many years. For those of you wanting to cut calories and fat, slice a lot of onions, enough to pretty much fill the crock, and put them in the slow cooker with no butter, no broth, no salt, no pepper, nothing. Just the onions. Cook them on LOW for 24 hours. Don’t stir them, don’t peek. Just set a timer and at 24 hours, take off the lid, stir them, and proceed.

    I freeze them in half cup servings and use them for all sorts of things, including delicious single serving French onion soup.






  38. So easy and they taste AMAZING!!!!






  39. This is almost the recipe I’ve used for the last 15 years and a) yes, it *IS* as easy as we’re saying and b) yes, it tastes as GREAT as we say it does! :-)

    By “almost,” I mean…

    • I absolutely *stuff* my slow cooker with onions. In fact, for the first hour or so, the lid doesn’t fit on the slow cooker. The reduction in onions as they cook is absolutely ridiculous, so I make sure there’re a ton of onions to start.

    • I only use butter, never any oils. I just think it gives the onions a significantly better flavor.

    • A bit of garlic paste (1-2 tsp.) never hurt anyone/thing.

    • I start the onions off with two hours on HIGH, then 4-6 hours on LOW. Turns out a great product, every time. Sometimes it takes the whole two hours to condense enough raw onions that the lid will fit on the slow cooker.

    • Don’t cook off the excess liquid at the end of the cooking time! When you note that you are boiling your onions rather than cooking them, just pour off the excess liquid into an air-tight container, let cool and then refrigerate or freeze. Use it 1:1 with beef broth for a robust French Onion soup, in casseroles, other soups, pot pies, stews, etc. It’s a fantastic and virtually free incredible ingredient.






    • Oh, and no skinny little fine cuts of onion for me. At best, you can call my Vidalias “rough cuts.” I found that no matter what I do, what scheme of cooking plan I use, fine-cut onions burn on me every time. So rough-cut onions it is… no burning, just beautiful browning with a sweet, caramelized product at the end.






  40. Can you can them after this process and if so, how long would they need to process?

    Thank you!