I love caramelized onions – as a topping for sandwiches, in soup, even in sauces (I puree them and it adds a special little something to gravies and sauces). They are great for making French onion soup – add broth and croutons and top with a little cheese.
Unfortunately it takes time to cook them down properly, and I always seem to want them when I have the least amount of time to make them.
The slow cooker turned out to be the perfect solution to my problem. I make them in batches and freeze them in small portions and then thaw them in the microwave when I want them. It’s a great way to use up onions if they are starting to turn soft.
This post contains affiliate links. I earn a small commission if you purchase an item via one of my links. Your purchase helps to support this blog at no additional cost to you and allows me to continue to provide delicious recipes and kitchen help. For more information click here.
I started by greasing the inside of my slow cooker with about 2 tablespoons of butter (you can use margarine to keep them vegan). I sliced five large onions into 1/4 inch slices, but you don’t have to do that many at a time. You probably want to use at least two onions so you have enough mass to absorb the heat of the slow cooker. I used my mandolin slicer, but you could do it with a large knife. Separate the slices into rings and place into the slow cooker. Don’t fill it more than 3/4 full. Set the slow cooker on low and let the slow cooker do it’s magic. It takes about eight hours, slightly less if you use fewer onions. I used a large spoon to stir the onions about every two hours.
This works with just about any type of onion, but white or yellow onions work best. Red onions and sweet onions tend to have more moisture in them so they take longer to cook and don’t always brown nicely.
That’s it – really. No other ingredients, no special steps. Just let the long slow heat do its work. You can store them in the fridge for up to three days or freeze them in small portions for several months.
If you found this recipe helpful or have any questions or comments please feel free to use the comments section below. If you want to see more good stuff from the Old Guy In The Kitchen click the “follow” button here on the blog or visit my other sites:
6 thoughts on “Slow Cooker Caramelized Onions”
I’ve had mine in the slow cooker for 6 hours and they haven’t turned brown at all. I have the cooker set for 8 hours so will they begging to brown soon?
Hi Jenni. It does take several hours to brown. If you continue to have issues please let me know and we can try to trouble shoot over messenger
This sounds like a great idea. I’m going to try it.
Enjoy. It takes time but is super easy
I used the mandolin and instead of greasing the slow cooker tossed the sliced onions with a combination of melted butter and olive oil (about 3 Tablespoons total).
Let them all sit in cold slow cooker at room temperature overnight and then cook on low in the slow cooker with lid on for 8 hours.
How did they turn out?