Slow Cooker Caramelized Onions are a great way to add flavor and texture to a ton of dishes. Buttery, sweet, and delicious, they are easy to make and store for later!

Caramelized Onion Recipe

These onions are just about the best thing you can make in a slow cooker! I could eat these as a side dish, but I like to keep a batch in the fridge to add to anything I’m cooking to make it just a little bit better.

I can’t resist them when they are golden brown and sweet. I can toss them in a quesadilla, throw on top of my avocado toast or a crostini, add them to some sliders or a grilled cheese sandwich, or mix them with these French onion meatballs.

The traditional way to make them to is to cook in a skillet while standing there stirring the whole time. But who has the time to do that? I know I don’t.

This slow cooker method is so much easier. I just sit back and enjoy these buttery caramelized onions later.

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large onions and a bit of butter on a marble surface

Ingredients Needed

Onions – Vidalia, or sweet onions work the best.

Butter – I use unsalted butter but use what you have. It doesn’t have to be melted butter to start with.

What is the best onion to use?

I like white, Vidalia, or sweet onions for this recipe. White onions are lower in moisture so they caramelize easier and quicker.

Red onions caramelize nicely but they have a strange color at the end. I prefer standard yellow onions.

Do I need to add oil?

You can use an oil like olive oil or peanut oil but I prefer good old fashioned butter. Just be sure to use real butter and not margarine. It has too much water in it.

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How to Make Crockpot Caramelized Onions

First: Slice onions no more than 1 inch thick. Separate the slices and add to a large slow cooker.

Second: Add the butter and give a quick stir to coat. Cook on low for 10 hours stirring occasionally.

slow cooker caramelized onions in a white pot

Third: The last hour or two, crack the lid so the juices can evaporate to get the jammy texture.

Fourth: Remove and cool. Store or enjoy!

For the full recipe and detailed instructions, please refer to the recipe card at the bottom of the post.

caramelised onions that are great in a delicious french onion soup

How long do they last?

Store them in an airtight container in the fridge for up to 5 days. Reheat in a saucepan or in the microwave.

Can I freeze these?

These onions are perfect for meal prep or making ahead. Cook a batch, cool completely, and store in freezer bags. Freeze them for up to 3 months.

Use ice cube trays to freeze in easy to make smaller portions for soups, stews, and dips.

Ways to Use Caramelized Onions

sliders & sandwich toppings
tapas bruschetta & crostini
top a wheel of brie
pizza topping
stews & soups
dips & spreads
top your chicken, pork chops, and steaks.

What’s the difference between caramelized onions and sauteed onions?

Sautéing is cooking until the onions are tender and clear or translucent in color. This method is used when cooking ground beef and onions for tacos or a casserole.

Caramelizing is cooking over low heat and allowing the sugar to cook until they are a deep golden brown and very sweet.

How thick do I need to slice the onions?

I like to use larger onions for less prep and keep the slices less than 1 inch thick. That way they retain their shape even if they cook down quite a bit.

I like to use larger onions for less prep and keep the slices less than 1 inch thick.

Tapas Tips & Tricks

The raw onions release a lot of liquid and it needs to cook off. Crack the lid to allow for evaporation. This gives the onions a jam texture like this tomato bacon jam.
Check in on them every now and then and give a stir.
Add balsamic vinegar, Worcestershire sauce, brown sugar, or a spirit for extra flavor!
Freeze them in small portions (ice cube trays are great for this) to easily add to recipes.
If your slow cooker gets a little hot on the edges and the onions start to burn, use a spatula to scrape them off and into the center of the pot.
Season with salt and pepper if you want but I like to keep mine plain.
Perfect for cooking a large amount of onions before they go bad.

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Don’t spend a couple of hours of cooking and stirring when you can let your slow cooker do all the work and you can have a large batch of perfect caramelized onions whenever you have a craving!