Some recipes are just so simple and yet are so worth it! Caramelized onions is definitely one of those recipes and so worth making. This caramelized onion recipe could not be easier to make. It’s also my favorite way to use up any leftover onions. 

Caramelized onions

What you need to make caramelized onions

That’s really no rocket science; for making caramelized onions you need…. drumroll please…. onions! While you can use red onions, yellow onions or sweet onions for this, I like to use regular yellow onions. The caramelization process makes sure that the natural sugars in the onions come out and make it super delicious and sweet. Do use large onions to make your peeling life easier.

There are ways to vary how you make them but let’s first get to the basics.

What you need to make caramelized onions

How to make

For making the caramelized onions you first need a large skillet or a Dutch oven. And you need to slice all the onions, which is always a pain. I like to do that using a food processor. It’s quicker and prevents me having to cry my eyes out. Now the fun part is that when I wear my contact lenses I can slice onions without issue but when I wear my glasses I start crying right away. My eyes can be sensitive like that and despite all the “solutions” you can find online, not one has really worked. Anyway, that’s beside the point. A food processor is my saving grace.

Once all the onions are sliced you add some olive oil and butter to the pan and place it on medium heat. You don’t want it to go to fast and burn the onions. The cooking process takes about 30 minutes so make sure that the onions don’t burn during that cooking time. You want them golden brown with some browned bits but definitely not burned. Burned onions become bitter, so be careful there.

First start by sweating the onions a bit for a couple of minutes, then turn down the heat and let them cook. Make sure to stir regularly across the bottom of the pan with a wooden spoon to make sure nothing sticks (using nonstick pans helps) 

Caramelized onions

After about 30-45 minutes the onions will naturally darken and become soft and sweet. The exact timing is hard to give as it depends on the type of onion you’re using plus the size of your onion slices. So just keep an eye on things. I like to add some fresh thyme to the pan as I think that is the perfect addition to this simple recipe.

Once the onions are browned enough add a splash of water to deglaze the pan and make sure all the delicious bits are getting out of the pan and into the onions. You can also use apple cider vinegar or balsamic vinegar for this.

Possible additions

Depending on what you want to use your caramelized onions for you can add some additional flavors like balsamic vinegar or a bit of brown sugar. Keep in mind that the onions already get a pretty sweet flavor (again depending of the kind of onion too) so be careful with adding more sweetness to it. 

Closeup onions

What can you do with caramelized onions?

Once you’ve made those sweet caramelized onions you can use it in various ways. Add them to your french onion soup for instance or make a french onion dip (caramelized onion dip coming up soon!) Adding them to your veggie burgers is always a great idea. You can add them to your favorite pizza or make a pissaladiere (which is basically a savory tart with loads of caramelized onions. Recipe will also follow soon)

Why do you have both butter and oil in this recipe?

Butter can burn rather quickly due to the milk solids in the butter, so in order to prevent that happening the combination of oil (you can use either avocado oil or olive oil) and butter is perfect. But if you want you can use either one of the two. Just keep an eye on things the entire time when using only butter. Bon Appetit has a good post on mistakes to avoid making these onions.

How long can you keep caramelized onions?

When saved in an airtight container you can keep the caramelized onions in the fridge for a few days. 

Can you make this in a slow cooker?

Yes you can! I have not done this but Gimme Some Oven has the recipe for that.

Caramelized onions

Caramelized onions

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Making your own caramelized onions is the perfect basic recipe for a whole lot of deliciousness
Decorative clock showing preparation time
Prep time 10 minutes
Cooking time 45 minutes
Total time 55 minutes

4 portions


  • 1000 gr yellow onions
  • 30 grams butter
  • large splash of olive oil
  • 3 sprigs of thyme

How to make caramelized onions

  • Cut the onions into thin rings. Melt the butter with the olive oil in the pan. Add the onions and thyme and cook between 30-45 minutes, over low heat until golden brown and soft.
  • Deglaze the pan with a little bit of water or vinegar.

Nutrition Information per portion

Calories: 154kcal | Carbohydrates: 23g | Protein: 3g | Fat: 6g | Saturated Fat: 4g | Polyunsaturated Fat: 0.3g | Monounsaturated Fat: 2g | Trans Fat: 0.2g | Cholesterol: 16mg | Sodium: 58mg | Potassium: 367mg | Fiber: 4g | Sugar: 11g | Vitamin A: 192IU | Vitamin C: 19mg | Calcium: 59mg | Iron: 1mg


The nutritional values above are calculated per portion. The details are based on standard nutritional tables and do not constitute a professional nutritional advice.

Did you make this recipe?Mention @insimoneskitchen_ or tag #insimoneskitchen!

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Simone van den Berg

Food blogger from the Netherlands. Loves good food. Likes to create healthy and easy recipes for daily use, but also loves the occasional sweet dish. Lives in the Netherlands with her two cats; Humphrey and Buffy. Profession: Food photographer, food blogger, recipe developer and nutritionist