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Home » Recipe Type » Dinner
4.7 from 9 reviews

Slow Cooker Caramelized Onions (with Yellow Onions!)

5 hours 10 minutes
onion
By: Pamela Reed
Posted:1/18/20
Updated:4/9/24
Jump to Recipe

Slow Cooker Caramelized Onions, cooked on high for 5 hours. Just mix yellow onions, butter, sugar and salt in a crockpot and come back to delicious buttery sweet caramelized onions! Freeze in ice cube trays to keep them for months. Save this recipe if you are growing onions in your garden!

closeup of spoon serving caramelized onions.

Slow Cooker Caramelized Onions

What’s not to love about sweet caramelized onions made in the slow cooker? They are so delicious and can be added to practically any meal. Even better, they are so easy to make! It’s as simple as chopping onions into slices, throwing them in the crockpot with butter, sugar and salt, closing the lid… and you’re done!

We grow lots of onions in our garden so this is one of our favorite ways to preserve them. After they are cooked in the crockpot, we transfer to ice cube trays and freeze.

Caramelized onions take 5-6 hours on HIGH in the crockpot. This recipe makes approximately 2-3 cups of caramelized onions.

Need them quicker? Try my Quick Caramelized Red Onions. Looking for more yellow onion recipes? Check out my Onion Sandwich, Fried Corn and Onions, Homemade Onion Powder and Bangers and Mash with Beef Onion Gravy. For red onions, check out my Red Onion Jam and Red Onion Chutney!

caramelized onions in ice cube trays.

Best onions for caramelizing

Yellow onions tend to be sweeter so they’re best for caramelizing. We grow “candy” yellow onions in the garden which have a rich sweet flavor.

Ingredients

  • Yellow onions, 3 pounds, peeled and sliced. You can adjust this recipe if you have more or less onions.
  • Butter, melted
  • Salt
  • Sugar
yellow onions on table.

How To Make Caramelized Onions in the Crockpot

This recipe calls for 3 pounds of sliced onions.  I use my 6 quart Slow Cooker and the onions take up about 75% of the space when they begin.  Peeling and slicing 3 pounds of onions is tough business so if you have sensitive eyes like me I suggest wearing sunglasses while doing this and opening a window if you live in an apartment.

Add all of the ingredients into a large slow cooker and stir so the butter coats the onions.

buttery onion slices in slow cooker.

Cook on HIGH until the onions are soft. For me this usually takes 5 hours.

closeup of cooked caramelized onions in slow cooker.

Serve with your favorite dish or freeze the onions for later (directions below). So easy, right?

spoon lifting caramelized onions up.

Freezing Caramelized Onions

Freezing caramelized onions is our main way to preserve them. Allow to cool and then place in ice cube trays to freeze. Once frozen, pop them out and then throw them in a freezer bag to freeze.

When ready to use them, grab a couple cubes out of the bag and defrost in the microwave.

Caramelized onions will last 6-8 months in the freezer.

caramelized onions in ice cube tray.

Pin for later:

Slow Cooker Caramelized Onions, cooked on high for 5 hours.  Just mix yellow onions, butter, sugar and salt in a crockpot and come back to delicious buttery sweet caramelized onions! Freeze in ice cube trays to keep them for months.  Save this recipe if you are growing onions in your garden!
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4.67 from 9 reviews

Slow Cooker Caramelized Onions (with Yellow Onions!)

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Slow Cooker Caramelized Onions, cooked on high for 5 hours. Just mix yellow onions, butter, sugar and salt in a crockpot and come back to delicious buttery sweet caramelized onions! Freeze in ice cube trays to keep them for months. Save this recipe if you are growing onions in your garden!
By: Pamela Reed
Prep Time: 10 minutes minutes
Cook Time: 5 hours hours
Total Time 5 hours hours 10 minutes minutes
serves 24

Ingredients

  • 3 pounds yellow onions peeled and sliced
  • 1/2 cup melted butter
  • 1 teaspoon salt
  • 1 teaspoon sugar

Instructions

  • Add everything into a large slow cooker and stir so the butter coats the onions completely.
  • Cook on high for 5-6 hours or until onions become soft and caramelized. My slow cooker usually takes 5 hours.
  • Serve with your favorite dish, store in the refrigerator for a few days or freeze to preserve. To freeze, allow to cool and then place in ice cube trays and freeze. When frozen, pop them out of tray and place in freezer bags to freeze. Defrost as you need them. Frozen caramelized onions can last 6-8 months.

Notes

This recipe makes approximately 2-3 cups of caramelized onions.

Nutrition Information:

Calories: 114kcal (6%)
Course: Side Dish
Cuisine: American
Diet: Vegetarian
Keyword: Slow Cooker Caramelized Onions
Vegetarian Fall, Summer
Did you make this?I love seeing what you’ve made! Tag me on Instagram at @BrooklynFarmGirl and don’t forget to leave a comment & rating below.

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4.67 from 9 votes (8 ratings without comment)

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  1. Matthew says

    October 12, 2020 at 10:02 am

    We have too many onions and this is a great way to save them for later.

    Reply
  2. Steve Warren says

    October 19, 2019 at 4:46 am

    The secret to tear free onion slicing is a very sharp knife.
    I start with a small serrated edged paring knife to top and tail the onions,
    then placing a now flat end on the cutting board, I slice the onion in half with a thin bladed small japanese cleaver – which I also use to slice the onions.
    Next I slip my thumb under the outer layer of the onion (inside the brown skin which may slip off anyway) and pry this layer off and discard it because it is often tough, sometimes a bit green and cooking doesn’t usually compensate for that.
    Then I place the onion half flat side down and slice away with the very sharp knife – and hardly ever get teary eyed. Well, not from cutting onions anyway!

    Reply
    • Pamela says

      October 21, 2019 at 11:26 am

      Hey Steve, thanks for sharing your tips!

      Reply
  3. Nisha @ Honey What's Cooking says

    April 8, 2017 at 2:46 pm

    OMG ,these look insanely good! Just wow.

    Reply
  4. [email protected] says

    April 7, 2017 at 10:20 am

    This is genius! You have changed the way I will caramelize my onions forever!

    Reply
  5. Cheyanne @ No Spoon Necessary says

    April 6, 2017 at 9:21 am

    I have a serious obsession with caramelized onions. Like, I will make VATS of the stuff, because i want to be able to eat it by serving spoon full and still have enough left over to use it in actual dishes. But, I’ve never tried making it in the slow cooker! For some reason I didn’t think it would turn out well, but obviously it does because yours looks amazing!!! SOOOO DOING THIS! Cheers, girl!

    Reply
  6. Anu - My Ginger Garlic Kitchen says

    April 4, 2017 at 3:07 pm

    Caramelized onions in a slow cooker for real? This sounds like a genius idea. Would love to try this recipe.

    Reply
  7. Amy (Savory Moments) says

    April 4, 2017 at 2:50 pm

    This is a terrific idea! It would be perfect for making all the onions for French onion soup ahead of time.

    Reply
  8. Angie@Angie's Recipes says

    April 4, 2017 at 5:00 am

    Didn’t even know that you can make caramelized onions in slow cooker…so cool! Definitely give this a try.

    Reply
  9. Sues says

    April 3, 2017 at 11:22 pm

    Oh yum!! I’ve never thought to caramelize onions in my slow cooker, but this is such an awesome idea!! I bet my kitchen would smell soooo delicious 🙂

    Reply
  10. Kayle (The Cooking Actress) says

    April 3, 2017 at 8:09 pm

    ooooh I love caramelized onions too–my knees would probably also buckle 😛

    Reply

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Hi! I'm Pamela, an artist Mom who shares family recipes. My farm is a 1,000 sq ft apartment in NYC. Let's make dinner together.

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