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.
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.
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.
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.
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
Ingredients
- 3-4 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
- 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.
- 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.
- 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”.
- Serve the onions immediately, or cover and refrigerate for up to 3 days. Or freeze for up to 3 months.
Notes
Did you make this?Let me know how it turned out in the comments below!
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!
I was sad when the last teaspoon was gone! ??
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?
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.
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.
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.
Lois,
What a great idea! I’m cooking some right now and will try that!
Thanks, God Bless!
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.
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!
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.
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.