18 Ratings
  • 5 star values: 12
  • 4 star values: 5
  • 3 star values: 1

Let your slow cooker do all the work of making beautifully caramelized onions. Freeze what you don't use right away so you'll have caramelized onions ready in a snap for soups, burgers, omelets, pizzas, and more.

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Ingredients

16
Original recipe yields 16 servings
The ingredient list now reflects the servings specified

Directions

  • Rub bottom and sides of slow cooker with 1/2 of the butter. Toss onions and salt with remaining butter in a bowl.

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  • Cook onions on Low until browned and sweet, about 10 hours.

Cook's Notes:

Substitute butter with olive oil, if desired.

After 10 hours of cooking, reserved liquid can be strained and used to make soup or sauce.

Onions can be cooked longer for a deeper brown and more concentrated flavor, if desired. To reduce further, leave the liquid in and cook, stirring occasionally, until the onions are darker brown and the liquid is almost completely cooked off, 4 to 5 hours.

Partner Tip

Try using a Reynolds® slow cooker liner in your slow cooker for easier cleanup.

Nutrition Facts

71 calories; 3 g total fat; 8 mg cholesterol; 170 mg sodium. 10.6 g carbohydrates; 1.3 g protein; Full Nutrition


Reviews (13)

Read All Reviews

Most helpful positive review

Rating: 5 stars
11/20/2016
So easy! I put them into the slow cooker the evening before and let them cook all night. The house did really smell in the morning and for a long time afterwards but if you put out a bowl of vinegar on your counter it quickly absorbs the residual smell. I used regular yellow cooking onions and didn't add any sugar which worked great! I have made this a few times and I prefer to make large batches and then freeze them in a few different portion sizes for later use. I don't plan to ever go back to the stove top method!
(3)

Most helpful critical review

Rating: 3 stars
05/12/2017
were a little mushy
18 Ratings
  • 5 star values: 12
  • 4 star values: 5
  • 3 star values: 1
Rating: 4 stars
10/09/2016
Instead of straining off the liquid (and onion sugars) just cook with the lid off on high stirring occasionally. I made these to go with some collards (which needed that extra sweetness from the onion to counter the bitterness of the greens). Worked beautifully!
(8)
Rating: 5 stars
11/20/2016
So easy! I put them into the slow cooker the evening before and let them cook all night. The house did really smell in the morning and for a long time afterwards but if you put out a bowl of vinegar on your counter it quickly absorbs the residual smell. I used regular yellow cooking onions and didn't add any sugar which worked great! I have made this a few times and I prefer to make large batches and then freeze them in a few different portion sizes for later use. I don't plan to ever go back to the stove top method!
(3)
Rating: 5 stars
11/28/2016
This was the easiest way to make carmelized onions I've ever tried. The up side was that they were perfect and tasted fantastic. The down side is that it takes 10 - 14 hours to completely carmelize the onions using the slow cooker. If done for 10 hours there is a lot of liquid to be drained off for use in another dish (French Onion soup maybe?). If cooked for the additional 4 hours with lid slightly off set the liquid evaporates and the onions become a deeper caramel color. If you don't need them right away this is the way to go as they can be frozen; otherwise they'll need to be done in the skillet which is definitely quicker but much more labor intensive.
(3)
Rating: 5 stars
11/13/2016
Great and easy to make. I used them in the slow cooker french onion soup recipe on this site. Started the evening before hitting the sack and in the a.m. added the rest for the soup. I would suggest adding a little sugar depending on the type of onions you use. Mine were the ordinary yellow onions
(2)
Rating: 5 stars
03/05/2019
3.5.19 Used the slow cook feature on my 6-quart Instant Pot®, and the uncooked sliced onions just about filled the pot. They cooked on “less” for about 16 hours. I then used the “saute normal” feature on the pot, and cooked down some of the onion liquid, but did reserve some for today’s dinner, French Dip sandwiches. In a word, these onions are DEEE-LICIOUS! Last night, used them on a grilled cheese and bacon sandwich, and over the weekend, they’ll be heading into some French onion soup. I scooped the caramelized onions into the cups of a muffin tin lined with paper cupcake liners, and then put them in the freezer. When they were frozen, I removed them the muffin tin, and transferred them to a gallon-size zip-lock bag. Caramelized onions add such incredible flavor and sweetness to so many dishes, but they do take some time to caramelize, often time you don't have for a weekday dinner. It is so convenient to already have them on hand, and they can be quickly defrosted in the microwave. If you have a food processor for slicing, this is so very, very simple to make; you just have to allow the slow cooker enough time to work its magic!
(2)
Rating: 5 stars
09/19/2016
I made this and the only thing is I did it overnight and so the edges of the slow cooker got sort of black. Other than that the onions were wonderful. I would do it again but during the day so they can be stirred once in a while. I really wasn't upset with the odor of the onions it wasn't that bad. Next time I would double the amount of onions. Might as well make a big batch. Nice that there is no sugar added. Just the sweetness of the onions.
(2)
Rating: 5 stars
01/24/2017
I loved the smell of the onions...I added thyme and a bay leaf to 3 large sweet onions and 3 small yellow onions. I shouldn't have added a tsp of sugar as it wasn't needed. they cooked down and caramelized wonderfully. I will always do this if I have the time. so easy to set and go.
(1)
Rating: 5 stars
02/09/2017
filled my 5 quart cooker with home grown onions and they were delicious! Put them over a roast beef on a sandwich (heated them in microwave for 30 seconds) and plan on freezing the rest for other things
Rating: 5 stars
08/20/2017
Onions turned out great. Doubled the recipe and used my bigger pot on low for 10 hours. Cooked outside on deck so house wouldn't get smelly.