Slow Cooker Caramelized Onions

Slow Cooker Caramelized Onions are the best kitchen shortcut! No more babysitting a skillet on the stove forever, your arm hurting from all the stirring. You can caramelize onions in the crock pot with a little butter and salt while you go about your day. They’re the perfect topping for sandwiches, burgers, and so much more!

 

Slow Cooker Caramelized Onions

I don’t know about you but I love love love onions!!! Roasted, fried, in salads and soups, there’s no wrong way to eat them.

And much like butter, caramelizing makes everything better. 

To use up the last of the crate I got from a friend, I made a big batch of slow cooker caramelized onions… and then finished them off myself in about 2 weeks…

Toast, sausage, hamburgers, burritos with chicken, burritos with cheese, burritos with just the onions — you get the idea!

I tried two different ways to caramelize onions in the crock pot, and just a minor change made a HUGE difference.

The first batch included just 1 tablespoon of sugar to get things going, and they were almost sickly sweet. The second (without sugar) came out perfect!

Ingredient Notes and Substitutions

• Onions – Any yellow onion is perfect for this caramelized onions slow cooker recipe, but it will work with white or red onions too.
  
  You could even use a mixture to create more depth of flavor!
  
• Butter – Use unsalted so you can control how much actual salt goes into the pot. And no margarine here, only real butter! You can use olive oil or a combination of both.
  
• Salt – This helps draw out the liquid from the onion slices and dissolve the natural sugars. Don’t skip it!

Tips and Tricks to Caramelize Onions in a Slow Cooker

• Make adjustments depending on the size of your crockpot.

The larger your crockpot, the more you’ll be able to add from the start.

When I used my 5 quart, I was only able to fit about three-quarters of my onion slices at first, but was able to add more as they started to reduce. When I use my 6-quart they fit perfectly.

It will take a few hours of cooking before they soften and reduce enough to add more, but it takes the full 8-10 hours to caramelize onion in a slow cooker.

• Stir occasionally to prevent sticking.

While this method is far more hands-off than the stovetop method, it still requires a little attention.

Stir caramelized onions in the crockpot every 2-4 hours or so to ensure they don’t stick to the bottom or sides — and so they brown evenly. Cooking on low you shouldn’t have any issues this way.

Cooking time will also vary based on the size of your crockpot and how much natural sugar is in your onions.

Prep Ahead

• Slice onions

Kitchen Tools You Will Need

• Slow Cooker – Great for soups, roasts, shredded chicken, and more! I love it in the cooler months, but it’s also great in the summer when you don’t want to heat up the whole house with the oven.
• Quality Knives and a big solid Cutting Board make prepping a breeze and are well worth the investment.
• Heat-Resistant Spoon or Spatula – Perfect for stirring and serving caramelized onion slow cooker style.

Serving Suggestions

The correct question is what can’t you put caramelized onions on?!

Have them ready for burgers, hot dogs, steak, chicken… anything you’d throw on the grill.

You can also use them to make homemade onion dip or mix into your favorite pasta dish. They’re especially yummy as a pizza topping!

Storing and Reheating Caramelized Onions from the Slow Cooker

Cool to room temperature, then transfer slow cooker caramelized onions to a jar or airtight container.

They will keep in the refrigerator for about a week, though I’ve stretched mine a few days past that before.

These also freeze beautifully! Once thawed, the texture is just like when they were first cooked.

It’s best to portion them into small freezer-safe baggies so you can thaw just what you need. Freeze for 3 months and thaw in the refrigerator.

Reheat caramelized onions on the stovetop over low heat for best results — no need for extra oil or butter!

Caramelized Onions in Crock Pot FAQ

Saved from our original post of this recipe in 2011:

Today is actually my Mommy’s birthday, and since we can’t be together I am hosting a virtual birthday party.  I love you Mommy! 

Happy Birthday and I wish I could be with you in person today. You are a gift to our family and everyone who knows you – you have touched so many lives!

We love you and count you as a blessing every day. Thank you for helping me become the woman, wife and mother I am today!  Have a beautiful Birthday!  XOXO

Enjoy!
With love, from our simple kitchen to yours.

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Slow Cooker Caramelized Onions

Donna Elick

Slow Cooker Caramelized Onions are sweet, delicious, and so easy to make! Make a big batch for sandwiches, burgers, hot dogs, and more!

5 stars from 2 reviews

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Prep Time 15 minutes mins

Cook Time 8 hours hrs

Total Time 8 hours hrs 15 minutes mins

Course Condiment

Cuisine American

Method Slow Cooker

Servings 8 make 4 cups

Equipment

• slow cooker

Ingredients

 

1x2x3x

• ▢ 4 tablespoons unsalted butter, melted (or olive oil)
• ▢ 1 teaspoon salt
• ▢ 8 large onions, halved and then sliced ⅛” – ¼” thick (about 3-4 pounds)

Instructions

 

• Add onions to a 6 quart slow cooker. Pour the butter (or oil) over the onions and sprinkle with the salt. Stir to combine.
• Cook on low 8-10 hours, stirring occasionally (every 2-4 hours). Caramelized onions will be a rich golden brown color.
• Remove the onions once they are caramelized to your preferred taste, remove from the crock pot. If they start burning and become incredibly aromatic, be sure to check them. Enjoy, they are so incredibly delicious. I am going to make another batch. Each batch makes approximately a pint of caramelized onions.

Donna’s Notes

Butter vs. Olive Oil: Both work great, but butter gives a richer flavor while olive oil keeps it vegan and adds a slightly different taste.

Salting: Salt helps draw out moisture from the onions and enhances the caramelization process. Don’t skip it!

Storing:

1. Refrigeration: Once cooled, transfer the caramelized onions to an airtight container. They can be stored in the refrigerator for up to one week.

2. Labeling: It’s helpful to label the container with the date you made them so you can keep track of their freshness.

Freezing:
1. Portioning: Divide the caramelized onions into smaller portions before freezing. Ice cube trays or muffin tins work well for this. Once frozen, transfer the portions to a freezer-safe bag or container.

2. Freezing: Place the portions in a single layer on a baking sheet and freeze until solid. Then, transfer them to a labeled freezer-safe bag or container. They can be frozen for up to 3 months.

3. Thawing: To use frozen caramelized onions, thaw them in the refrigerator overnight or reheat them directly from frozen in a pan over low heat.

Nutrition

Serving: 1 | Calories: 94cal | Carbohydrates: 10g | Protein: 1g | Fat: 6g | Saturated Fat: 4g | Cholesterol: 15mg | Sodium: 296mg | Sugar: 5g | Fiber: 2g | Calcium: 27mg | Iron: 0.2mg

All nutritional information is based on third party calculations and is only an estimate. Each recipe’s nutritional value will vary depending on the ingredients used, measuring methods, and portion sizes.

Tried this recipe?Let us know how it was!

Originally Published September 2011, updated and republished May 2024

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