A twist on a classic, these caramelized onion mashed potatoes are a decadent side dish that everyone will love! Creamy mashed potatoes combined with rich and buttery caramelized onions, this flavorful mashed potatoes recipe is perfect for the holidays or just for dinner!

Mashed potatoes are truly the best side dish. I also love the sweet and rich flavors of caramelized onions, so I thought, why not combine them?! This caramelized onion mashed potatoes recipe is absolutely the best. They’re so good that I think that they’ll definitely become a staple on your dinner table.

Overhead view of caramelized onion mashed potatoes in a pot topped with butter, chives, and more caramelized onions.

Why You’ll Love This Recipe

It’s very easy to make. Mashed potatoes are pretty easy on their own, and caramelized onions come together easily as well. They take some patience, but if you stir, you can make caramelized onions!
They’re so flavorful! The sweet, rich and buttery flavors of caramelized onions pair so nicely with the creamy and fluffy mashed potatoes. I also add parmesan cheese to the mashed potatoes for some extra tangy and sharp flavor to cut through the sweet richness.

Ingredients You’ll Need

Ingredients needed to make caramelized onion mashed potatoes.

butter & oil — I like to caramelize my onions with both butter and oil. The butter adds flavor, and the olive oil keeps the butter from burning. You’ll also need butter for the mashed potatoes.
onions — depending on how much onions you want in your caramelized onion mashed potatoes, use 4 to 5 yellow onions.
potatoes — use your favorite potatoes! I’m using russet potatoes, but I also like to use a mixture of starchy russet potatoes and creamy Yukon gold potatoes for a change of texture. Plus, during the holiday season, you might have to get a variety thanks to low stock. Avoid waxy potatoes (like white potatoes and red potatoes), as they’ll be gummy when mashed.
parmesan cheese — adding parmesan cheese to mashed potatoes will give them a sharp, nutty savory to contrast the rich creaminess.
milk or heavy cream — depending on how rich you want your potatoes.
salt — I use kosher salt.
chives — optional for a pop of color.

How to Make Caramelized Onion Potatoes

Set of two photos showing onions in a skillet, before and after caramelizing.

Heat the butter and oil in a large skillet over medium heat. Add the onions and sauté for 5 minutes or until the onions have softened.
Reduce the heat to medium-low and cook for around 40 to 50 minutes. Stir the onions with a wooden spoon or spatula every few minutes or until the onions are golden brown and caramelized to your liking. Add more butter or oil as needed.

Set of two photos showing potatoes added in a pot then mashed with parmesan cheese and butter.

As you caramelize the onions, bring a (covered) pot of salted water with the potatoes to a boil. Once it has reached a boil, slightly uncover the pot and simmer until the potatoes are fork-tender, about 10 to 15 minutes, depending on how large the potatoes are.
Drain the potatoes and add them to a large bowl. Mash with a potato masher (or a potato ricer) until there are no more large chunks.
Add the butter, parmesan cheese, milk or cream, and salt. Continue to mash until smooth.

Set of two photos caramelized onions added to the potatoes and stirred to combine.

Add the caramelized onions and use a spatula to stir to make sure everything is evenly distributed. Add additional salt and pepper and top off with chives as desired.

A spoonful of caramelized onion mashed potatoes lifted up.

Recipe Tips and Notes

Season with additional garlic powder and onion powder if desired.
Make sure to boil the potatoes in cold water from the start, and not add potatoes to the boiled water. This ensures the potatoes cook evenly.
I usually let my potatoes sit in a colander for a couple of minutes to ensure they are fully drained and dry before I mash them. This will help keep the mashed potatoes from being watery.
I add around 1-2 tablespoons of salt to the water.
You can dice the caramelized onions, so you get a little bit of onion with every bite. Alternatively, you can dice the onions before caramelizing them. I just prefer slicing them and having the strands of onion in the mashed potatoes.
Holidays can be tricky! You can make these mashed potatoes plant-based by using plant-based butter, and instead of parmesan, nutritional yeast.
I like to hold off a bit of the caramelized onion to place it on top for a prettier presentation!

Caramelized onion mashed potatoes in a pot topped with butter, caramelized onions, and chives.

Make Ahead Tips

This creamy caramelized onion mashed potato recipe yields enough for six servings. If there are leftovers or if you plan on making it ahead of time, here’s my recommended way for storing and warming up and reheating mashed potatoes so they aren’t dry!

Make Ahead: once cooled, store the creamy caramelized onion mashed potatoes in an airtight container for up to 4 days in the fridge.
Reheat: reheat the mashed potatoes in the microwave or on the stovetop. You can add a few splashes of cream into the saucepan as you stir when reheating to help loosen it up.
Reheat in the oven: You can reheat the mashed potatoes in the oven at 350F, uncovered, with extra cream stirred in and extra butter on top for about an hour. The extra liquid should evaporate and your mashed potatoes will warm up without being dry.

Serving Suggestions

Need some ideas for what to make with this mashed potatoes with caramelized onion recipe? Here are some mains I love!

Caramelized Onion Mashed Potatoes

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Prep Time: 10

Cook Time: 45

Total Time: 55

Servings: servings

Ingredients

For the Caramelized Onions

4 tablespoons butter, unsalted
2 tablespoons olive oil
4 to 5 yellow onions, sliced

For the Mashed Potatoes

3½ pounds russet potatoes, or Yukon gold
4 to 5 tablespoons butter, unsalted
1 cup parmesan cheese, shredded
½ cup milk, or heavy cream
1 teaspoon salt
chives, optional garnish

Instructions

Heat the butter and oil in a large skillet over medium heat. Add the onions and sauté for 5 minutes or until the onions have softened.
Reduce the heat to medium-low and cook for around 40 to 50 minutes. Stir the onions with a wooden spoon or spatula every few minutes or until the onions are golden brown and caramelized to your liking. Add more butter or oil as needed.
Around 20 minutes into making the caramelized onions, bring a (covered) pot of salted water with the potatoes to a boil. Once it has reached a boil, slightly uncover the pot and simmer until the potatoes are fork-tender, about 10 to 15 minutes, depending on how large the potatoes are.
Drain the potatoes and add them to a large bowl. Mash with a potato masher (or a potato ricer) until there are no more large chunks.
Add the butter, parmesan cheese, milk or cream, and salt. Continue to mash until smooth, and then add the caramelized onions.
Using a spatula, stir until everything is evenly distributed. Add additional salt and pepper and top off with chives as desired.

Tried this recipe?Did you make this recipe? I’m always so happy to hear about it! I’d love to see how it turned out. Tag me at @CarmysHungry on Instagram so I can see it! If you enjoyed the recipe, I’d really appreciate a comment with a 5 star rating! ♥

Nutrition Per Serving

Author: Carmy

Course: Side Dish

Cuisine: American

Nutrition Disclaimer

More Holiday Side Dishes to Try

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