Recipe By foodelicious
Published Apr 2nd
Prep 10m Cook 10h Additional - Ready In 10h 10m
Servings 1 quart Calories 70.8

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.

Recipe Ingredients

  • ¼ cup melted butter, divided
  • 8 onions, thinly sliced
  • 1 teaspoon salt

Cooking Directions

  1. 1 Rub bottom and sides of slow cooker with 1/2 of the butter. Toss onions and salt with remaining butter in a bowl.
  2. 2 Cook onions on Low until browned and sweet, about 10 hours.

Nutrition Facts

  • Calories 70.8
  • Carbohydrate 10.6 g
  • Cholesterol 7.6 mg
  • Fat 3 g
  • Fiber 1.9 g
  • Protein 1.3 g
  • Saturated Fat 1.9 g
  • Sodium 170.3 mg
  • Sugar 4.8 g

Chef'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.


  1. 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 - Read more ...
  2. 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.
  3. were a little mushy
  4. 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 - Read more ...
  5. 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 - Read more ...
  6. 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 - Read more ...
  7. 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 - Read more ...
  8. 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!
  9. 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 - Read more ...