Slow Cooker Caramelized Onions

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Thanks to the magic of slow cooking, you can create these wonderfully buttery Slow Cooker Caramelized Onions with almost no effort at all.

a close up photo of caramelized onions in a small jar on a wooden tabletop with a red and white striped napkin in the background

Slow Cooker Caramelized Onions

I have made these slow-cooker caramelized onions twice in the past couple of months. They’re fabulous as a topping on burgers and steaks, and they are heavenly in an omelet or quesadilla.

The crockpot is an absolute game-changer in how to cook caramelized onions. They require a lot less tending. And, the result is a mountain of mouthwatering, tender onions loaded with flavor.

caramelized onions fill this small jar to the brim in this photo

Slow cookers or crockpots are an appliance of which I have more than one. If you are an avid slow cooker user like I am, you might understand the need for more than one. So, let’s talk about my favorites:

First up is this 6-quart slow cooker that has a locking lid. These crockpots are fantastic for transporting foods. Mine has gone everywhere from church potlucks to barbecues, game nights to Thanksgiving dinner. However, fair warning, these slow cookers run crazy hot. Low is closer to a boil than a simmer, the warm setting actually simmers. So trust me when I say HIGH is high.

My everyday slow cooker is this 8-quart Crockpot. It’s my go-to appliance for cooking large roasts and big batches of chili. Fun fact: did you know that a full 4-quart cooker, actually cooks more slowly than a half-full 8-quart cooker?

For just cooking a few pounds of chicken to shred for enchiladas or other smaller recipes, this 3-quart version is perfect.

Thanksgiving has become a breeze since I have mastered how to hold all of the side dishes using these medium-sized round slow cookers.

If you aren’t a fan of the idea of keeping more than one slow cooker in the house, these CrockPockets are a game-changer when it comes to preparing and holding multiple dishes at the same time. They slide into a standard 6-quart crockpot, dividing it into two sections that are perfect for serving different side dishes or keeping taco fillings warm for parties.

An image of a small jar containing caramelized onions with an image of a red slow cooker in the background

How to Cook Caramelized Onions

You’ll need the following ingredients to make this recipe:

  • yellow onions
  • butter
  • olive oil
  • kosher salt
a shot of the interior of the crockpot with the oil and butter added

Set the crockpot to high heat and add the butter and olive oil. Then, slice the onions and add them to the crockpot. Sprinkle with salt.

Toss the onions to coat with the oils and salt. Let them cook with the lid OFF. Stir them occasionally throughout the day, scraping the sides each time.

This is where I insert a word of caution: Do not attempt to cook a tiny batch of onions in a large crockpot. They will not caramelize the same way. They will get crispy and if you aren’t carefully watching them, they may burn. (That said, we actually enjoyed the crispy onions, but they weren’t the goal here.)

One more thing to note, caramelized onions are about as fragrant as food gets while they are cooking. I usually place the crockpot near an open window or run a vent while they are cooking throughout the day.

the onions have been added to the slow cooker in this process shot

When the onions are browned and soft to your liking, turn off the heat. Serve warm or place in an airtight container and store in the refrigerator. Total cook time will vary for different slow cookers. But, it should take about 8 hours.

To freeze the cooked onions, separate them into ½ cup portions and store them in airtight containers or zip-close freezer bags. Thaw in the refrigerator before using.

tossing the onions in the slow cooker as they cook

Crockpot Caramelized Onions

If you don’t have time to make these crockpot caramelized onions, then check out this recipe for air fryer onions. It’s a quick way to get tender, yet crispy edged onions to top a burger or add to an omelet.

You can also saute them for a topping or as a stand alone side dish like these quick sauteed peppers and onions. Sauteing is one of my favorite ways to quickly prepare vegetables.

If you’re looking for something different, these creamed pearl onions create a rich and savory dish that complements a variety of main courses, particularly during holiday meals.

a process shot of stirring the caramelized onions as they finish cooking in the slow cooker

For those who love having onions in the mix, I definitely recommend you try this recipe for sweet and spicy chicken stir fry. And, this steak stir fry with mushrooms is fabulous.

And, this simple mushroom spaghetti sauce trumps anything you can buy in jars or cans at the grocery store. It gets rave reviews every time!

a top down photo of finished caramelized onions in the slow cooker
caramelized onions fill this small jar to the brim in this photo

Slow Cooker Caramelized Onions

Thanks to the magic of slow cooking, you can create these wonderfully buttery, caramelized onions with almost no effort at all. They're great on their own, or as a topping!
Prep Time: 5 minutes
Cook Time: 8 hours
Total Time: 8 hours 5 minutes
Servings: 12

Ingredients 

  • 4-5 large yellow onions about 6 cups
  • 3 tablespoons butter
  • 3 tablespoons olive oil
  • ¼ teaspoon kosher salt

Instructions

  • Set the crockpot to high heat and add the butter and olive oil. Slice the onions and add them to the crockpot. Sprinkle with salt.
  • Toss the onions to coat with the oils. Let them cook with the lid OFF. Stir the onions occasionally throughout the day, scraping the sides each time.
  • When the onions are browned and softened to your liking, turn off the crock-pot. (This should take about 8 hours.) Serve warm or transfer to an airtight container and store in the refrigerator.

Notes

Total cooking time is approximately 8 hours, but that will vary for different slow cookers and crock-pots.
To freeze the cooked onions, separate them into ½ cup portions and store them in airtight containers or zip-close freezer bags. Thaw in the refrigerator before using.
 

Nutrition

Calories: 88kcal · Carbohydrates: 7g · Protein: 1g · Fat: 6g · Saturated Fat: 2g · Polyunsaturated Fat: 0.5g · Monounsaturated Fat: 3g · Trans Fat: 0.1g · Cholesterol: 8mg · Sodium: 74mg · Potassium: 118mg · Fiber: 1g · Sugar: 3g · Vitamin A: 89IU · Vitamin C: 6mg · Calcium: 19mg · Iron: 0.2mg
Tried this recipe?Mention @bestvegetablerecipes or tag #bestvegetablerecipes!

white text has been overlaid this image of a glass jar containing caramelized onions. it reads: "Slow Cooker Caramelized Onions"

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  1. Sandra Hachey says

    Hi have not tried this recipe yet will be doing so. Before I start I was wondering if you could double this recipe and they would turn out pretty much the same. Do not want to waste any onions if chance they won’t. Have run into some recipes were they advise not to double but do to batches of things. My husband loves onions and where you say you could freeze or bottle them Iwould like to do up enough to have for him for different things I cook. Please advise your opinion on this. thank you

    • Mary says

      Yes, this can be multiplied easily. You can fill the crockpot to the top and they will cook down nicely. They may take a little longer to caramelize, but it won’t be significantly different, Sandra.