These Caramelized Onion Mashed Potatoes are unlike any other mashed potatoes you’ve ever had! They’re perfectly rich, creamy, cheesy, and the addition of the caramelized onions really takes them over the top! These potatoes are an elevated side dish perfect for holiday meals but you’ll crave them for weeknight dinners, too.

caramelized onion mashed potatoes in serving dish with spoon

Delicious Caramelized Onion Mashed Potatoes

This may be the only way you want to eat mashed potatoes from now on!

Is there anything better than a big bowl of warm mashed potatoes? The ultimate comfort food!

I love all the classic options like my slow cooker mashed potatoes or even my brown butter mashed potatoes but these caramelized onion mashed potatoes are next level!

Think French onion soup meets the creamiest mashed potatoes you’ll ever taste. Oh, and of course there’s plenty of gruyere cheese stirred in with those caramelized onions. They’re even better than you’re imagining, and they’re super easy to make!

— Ashlea

caramelized onion mashed potatoes ingredients

Ingredients You’ll Need

Butter: the milk solids kickstart the browning process and add rich flavor to the onions that you don’t get with just oil alone. Feel free to use vegan butter instead of traditional butter if needed.
Yellow Onions: I prefer the sweet flavor of yellow onions, but white onions will also work in a pinch.
Russet Potatoes: these are always my potato of choice when it comes to mashed potatoes. They give you a perfectly creamy mash that is so good.
Garlic: good mashed potatoes need plenty of fresh garlic, in my personal opinion. Don’t worry, you won’t have to do any mincing. Just let the whole cloves cook alongside the potatoes while they simmer.
Herbs and Spices: plenty of salt and pepper are a must. Then, I finish with fresh chives and fresh thyme for a pop of freshness.
Butter: a MUST in any good mashed potato recipe!
Half and Half: this helps combine the ingredients, adding rich flavor and creating a super creamy consistency. Whole milk will also work if preferred. You can also use a non-dairy milk such as cashew milk or coconut milk.
Gruyère Cheese: this gives the mashed potatoes the best flavor and helps make them super creamy. If you can’t find gruyère you could also use a sharp cheddar cheese. Or, use a plant-based cheese, or omit it completely to keep these mashed potatoes dairy-free.

caramelized onions being stirred into mashed potatoes

How to Make Caramelized Onion Mashed Potatoes (in 5 Steps!)

Step One: Cook the sliced onions low and slow in oil and butter over medium-low heat, stirring frequently until they are a deep golden brown color.

Step Two: Boil the potatoes and garlic in a pot of salted water, and cook until fork-tender. Then, remove the potatoes from the heat and drain the water.

Step Three: Transfer the potatoes and garlic back to the warm pot, and mash to combine. Add salt, butter, half and half, and black pepper, and continue to mash until creamy.

Step Four: Add half the caramelized onions to the pot along with the Gruyère cheese, and gently fold to combine. Add more half and half if needed for a creamier consistency, and season to taste.

Step Five: Transfer the mashed potatoes to a serving dish, add the remaining caramelized onions on top along with chives, thyme, butter, and grated Gruyère. Serve warm!

Serving Suggestions

I’ve yet to find much that these caramelized onion mashed potatoes don’t pair well with. They’re the perfect side dish alongside holiday mains like maple honey glazed ham or simple roasted spatchcock turkey.

Or, for everyday meals, they’re delicious with main courses such as:

How to Store and Reheat

Store: Transfer the cooled potatoes to an airtight storage container, and store them in the fridge for 3-4 days. I do not recommend freezing this recipe!

Reheat: You can easily reheat these potatoes in the microwave on high for 30 seconds to 1 minute at a time. You can add a bit of extra half and half when reheating if you like.

caramelized onion mashed potatoes in serving dish topped with butter

More Delicious Potato Recipes

I hope you give this Caramelized Onion Mashed Potatoes Recipe a try! It’s cheesy, savory, creamy, and so delicious! If you do give this recipe a try, let me know! Leave a comment with a star rating below. You can also snap a photo & tag @allthehealthythings on INSTAGRAM. Your reviews and ratings help support All the Healthy Things and make it possible for me to continue to create the recipes you trust and love.

Caramelized Onion Mashed Potatoes

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Author: Ashlea Carver
Prep Time: 20 minutes
Cook Time: 50 minutes
Total Time: 1 hour 10 minutes
Yield: 6 1x
Category: Sides
Method: Stovetop
Cuisine: French inspired
Diet: Gluten Free

Print Recipe

Description

Ingredients

Units Scale

For the Onions

2 tablespoons olive oil
1 tablespoon butter
3–4 large yellow onions, sliced 1/4 inch thick
1/4 teaspoon kosher salt

For the Potatoes

3 pounds russet potatoes, peeled and diced
4 cloves garlic, peeled and smashed
2 teaspoons kosher salt (divided), plus more to taste
4 tablespoons unsalted butter, plus more for serving
3/4 cup half and half
1/4 teaspoon black pepper
4 oz gruyere cheese, grated (plus more for topping)
thinly sliced chives, for garnish
fresh thyme, for garnish

Instructions

Make the Caramelized Onions: Heat a large pan with a lid to medium-low heat. Once hot add 2 tablespoons of olive oil and 1 tablespoon of butter. Add the onions to the pan and stir and then add the salt. Cover the pan and let the onions cook for 30-40 minutes, stirring every 5 minutes or so until the onions are a deep caramelized golden brown.
Cook the Potatoes: Add the potatoes, garlic, and one teaspoon salt to a large pot and cover with cold water. Bring the potatoes and garlic to a boil and let them cook until fork tender, roughly 15-20 minutes. Once tender, remove the potatoes from the heat and then drain completely.
Transfer the fully drained potatoes and garlic back to the warm pot and use a potato masher or hand mixer to mash the potatoes.
Add the remaining salt, butter, half and half, and black pepper and continue to mash until the potatoes are fully mashed and creamy.
Next, add half the caramelized onions and all of the grated gruyere to the mashed potatoes and fold into the potatoes until well combined. You can add a bit more half and half if you prefer for any even creamier consistency. Give the potatoes a taste and adjust the amount of salt and pepper to your taste.
Transfer the mashed potatoes to a serving dish. Top with the remaining caramelized onions, chives, thyme, and a bit more butter and grated gruyere before serving.

Notes

Store: Transfer the cooled potatoes to an airtight storage container, and store them in the fridge for 3-4 days. I do not recommend freezing this recipe!

Reheat: You can easily reheat these potatoes in the microwave on high for 30 seconds to 1 minute at a time. You can add a bit of extra half and half when reheating if you like.