How to Make Caramelized Onions

Making caramelized onions requires some patience, but it’s a simple process that anyone can master! This post will explain how to make caramelized onions four ways, plus the many ways you can use these jammy onions! 

What Are Caramelized Onions? 

Even if you’ve never made caramelized onions yourself, chances are good that you’ve eaten them before! 

Caramelized onions are essentially thinly sliced onions that have been cooked low and slow until they’re deeply golden in color and super sweet and jammy in flavor. 

Because their texture is so soft, caramelized onions are perfect for piling atop burgers, stirring into a creamy dip, or mixing into a rich soup. 

Making perfect caramelized onions at home isn’t hard, but it does require patience. I prefer making caramelized onions in a skillet, but I’ll walk you through three additional methods for preparing caramelized onions in this post. 

Caramelized vs. Sauteed Onions 

Before I explain how to caramelize onions, I wanted to briefly touch on the difference between sauteed onions and caramelized onions. 

• Sauteed onions: only take about 10 minutes to prepare in a skillet over higher heat. They’re much firmer in texture, hold their shape well, and have a distinctly onion flavor. 
• Caramelized onions: take closer to 40+ minutes to prepare over lower heat. They’re very sweet with minimal onion flavor, are deep brown in color, and are soft and jammy in texture. 

What You’ll Need to Caramelize Onions 

The exact ingredient ratios you’ll use will vary depending on the method you’re using to make caramelized onions. 

However, the ingredients you’ll need for any basic recipe for caramelized onions are: 

• Butter or olive oil — Butter is more flavorful, but either works. 
• Onions — A 3-pound bag makes roughly 2 cups caramelized onions. 
• Salt — Kosher salt is preferred, but any variety may be used. 
• Heavy-bottomed skillet or pot — Use something with high sides as the pile of onions starts out quite high. 

For the complete ingredient list and detailed instructions, scroll to the bottom of this post for the FREE printable recipe card.

What Are the Best Onions for Caramelized Onions? 

You may use any type of onion, but yellow and sweet onions caramelize the most easily. However, red onions also caramelize well and have a slightly different flavor. 

How to Make Caramelized Onions 4 Ways 

There are four main ways to caramelize onions: on the stovetop, in the oven, in an Instant Pot, or in a slow cooker. 

In my opinion, the best way to caramelize onions is on the stovetop. This method requires the most babysitting, but it’s the traditional method for caramelizing onions and creates perfect results every time. 

However, I’ll walk you through the various methods for caramelizing onions so you can choose which you feel the most comfortable with. 

Before following the instructions listed below, you’ll need to thinly slice the onions. It doesn’t really matter how you cut the onions, but cutting the onions in half and then cutting ⅛-inch thick half moons is the most common method. 

1. Instant Pot Caramelized Onions 

Making caramelized onions in an Instant Pot isn’t that much quicker than making them on the stovetop, but you won’t have to stand over the onions the entire time to ensure they don’t burn. 

1. Slice the onions thinly (about ⅛ inch). 
2. Melt butter or olive oil in Instant Pot on Saute function. 
3. Once melted, add onions and stir to coat. Add salt. 
4. Cover and cook for 20 minutes on Manual setting. 
5. Quick release the steam. 
6. Saute uncovered for another 20 minutes, stirring every 5 to 10 minutes. 

How long does it take to caramelize onions in an Instant Pot? 

Instant Pot caramelized onions take about 40 minutes total. Note that the Instant Pot will need to pressurize and depressurize, which will add to the total cook time. 

2. Slow Cooker Caramelized Onions 

This is arguably the easiest way to make caramelized onions, but it’s also the most time-consuming. However, you won’t have to stir the onions often and can make a big batch for later! 

1. Add 3 pounds of thinly sliced onions to a slow cooker. 
2. Drizzle with melted butter or olive oil. 
3. Cook on low for 8 to 10 hours. 
4. Season with salt. 
5. Continue cooking for another 3 hours, or until onions are deep brown and caramelized. 

Tip: If your onions look watery after 8 to 10 hours of cooking on low, crack the lid of your slow cooker slightly to let some of the steam escape during the remaining 3 hours of cooking. 

How long does it take to caramelize onions in a slow cooker? 

It takes roughly 11 to 14 hours on low. Don’t cook the onions on high to speed up the process, as that may cause the onions to burn. 

3. Stovetop Caramelized Onions 

Don’t walk away from the stove when making homemade caramelized onions! This is my preferred method for caramelizing onions (and probably the most common method used), but it does take time and constant babysitting. 

1. Slice the onions thinly (about ⅛ inch). 
2. Add butter or oil to a pot over medium-low heat. 
3. Once melted, add the sliced onions. 
4. Cook for about 10 minutes, stirring often. 
5. Then, stir in the salt. Reduce the heat to low. 
6. Let the onions continue cooking over low heat. Stir only every 5 to 10 minutes. You want the onions to develop color evenly and not burn, but you don’t want to disturb them often or else they won’t caramelize! 
7. When very dark brown and sweet in flavor, remove from heat. 

How long does it take to caramelize onions on the stove? 

It generally takes about 50 to 55 minutes to caramelize onions on the stovetop over medium-low heat. 

4. Oven Caramelized Onions 

Making caramelized onions in the oven is incredibly easy and requires minimal work on your part, but the results can vary. Some onions may be perfectly caramelized while others may be firmer in texture and not as jammy. 

However, if having a few less-than-perfect caramelized onions doesn’t bother you, this is a great method to employ if you don’t want to stand over the stove for 40 minutes. 

1. Preheat the oven to 375F. Line a rimmed baking sheet with parchment paper. 
2. Place the thinly sliced onions on the prepared baking sheet. Toss with olive oil and a splash of water, then season with salt. 
3. Bake for 40 to 50 minutes. Be sure to stir the onions every 10 minutes. 
4. You’ll know the onions are done when they’ve reduced in size and are deep golden in color. 

How long does it take to caramelize onions in the oven?

It’ll take about 40 to 50 minutes at 375F. 

The above is simply a quick summary of this recipe. Check out the full recipe in the free printable recipe card at the bottom of this post for all the detailed instructions.

Flavoring Caramelized Onions 

Caramelized onions are delightfully sweet and savory on their own, but you can amp up the flavor further by deglazing the pan with broth, wine (any kind), or balsamic vinegar. 

Add the liquid to the pan at the end of the cooking time to release the golden bits stuck to the bottom of the pan (called fond). Let the onions cook for a few more minutes to let the liquid cook off. (You don’t want the onions to be wet!) 

In addition to deglazing the pan, you can also add fresh herbs, brown sugar, or additional spices to the onions about halfway through the cooking process. 

How Long Do Caramelized Onions Last? 

If stored in an airtight container, caramelized onions will last up to four days in the fridge. 

Can You Freeze Caramelized Onions? 

Yes, you can freeze homemade caramelized onions for up to 3 months. 

Consider freezing them in small freezer bags or even ice cube trays so you can portion out exact servings later on. Having smaller quantities in the freezer is ideal for making dips and spreads, or for using atop burgers and sandwiches. 

To thaw frozen caramelized onions, place them in fridge. The exact amount of time needed to thaw the onions will depend on the amount you froze. 

Tip: Do NOT thaw frozen caramelized onions in the microwave as that could compromise the texture of the onions. 

FAQs About Caramelizing Onions 

Should You Add Sugar to Caramelized Onions? 

You may add about 1 teaspoon of granulated sugar to 3 pounds of sliced onions to speed up the caramelization process and add flavor. However, it’s not necessary as the sugars naturally found in the onions will caramelize over time. 

Should You Use Butter or Oil to Caramelize Onions? 

Either works! Butter adds more flavor, but ultimately it doesn’t matter which you use. 

If using oil, olive oil is recommended. Don’t use a strongly flavored oil like sesame or coconut. 

Should You Stir Caramelized Onions? 

Not very often. After the initial 10 minutes of sauteing, you should stir them only every 5 to 10 minutes. This ensures that they caramelize evenly without burning. 

Should You Cover the Pan When Caramelizing Onions? 

No, leave the lid off! If you cover the pan, the onions will steam rather than caramelize. 

How Should You Slice Onions for Caramelized Onions? 

Honestly, it doesn’t matter. Thinly sliced half moons is the most common method, but so long as the onions are thinly sliced you can cut them into any shape you’d like. 

Can You Caramelize Chopped Onions? 

Yes, just keep the onions over low heat. Smaller pieces of onion tend to burn more easily so keep an eye on your pan. 

What’s the Best Pan for Caramelized Onions? 

A stainless steel or cast iron pan with high sides is preferred. Use a heavy-bottomed skillet or pot that distributes the heat evenly. Cheaper skillets or pots won’t work as well, as they’re thinner on the bottom and often cause onions to burn. 

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Photography: photos taken in this post are by Rachael from Set the Table.