Name: French Onion Mashed Potatoes Recipe
Prep time: 1 h 10 min
Cook time: 20 min
Total time: 1 h 30 min
Cuisine: French-American
Ingredients: 6 tablespoons Simply Nature Organic Unsalted Butter; 4 sweet onions, thinly sliced; Kosher salt, to taste; 5 pounds russet or Yukon gold potatoes, washed and peeled; 12 tablespoons Simply Nature Organic Unsalted Butter; 1 ½ cups Friendly Farms Heavy Whipping Cream; 8 ounces Emporium Selection Le Gruyere Cheese, freshly grated; 1 to 2 teaspoons salt; Freshly ground black pepper, to taste

Jump to Recipe· 4.6 from 84 reviews

If you’re looking for a side dish that takes classic mashed potatoes up a notch and makes your dinner table feel downright fancy, you’ve got to try this French Onion Mashed Potatoes Recipe. I absolutely love how the sweet, deeply caramelized onions blend with creamy potatoes and melted Gruyère, creating a flavor combo that’s comforting yet sophisticated. Trust me, once you try it, you’ll want to make it again and again!

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Why You’ll Love This Recipe

Rich, Complex Flavor: The caramelized onions add a deep, sweet umami taste that transforms regular mashed potatoes into something incredible.
Creamy, Buttery Texture: Using plenty of butter, heavy cream, and Gruyère cheese gives the dish luxurious creaminess that everyone adores.
Comfort Food with a Twist: It feels classic and cozy but has a gourmet touch that impresses guests and family alike.
Versatile for Any Occasion: Whether it’s a weeknight dinner or a holiday feast, this recipe always fits right in.

A close-up image of a dish showing a creamy, pale yellow mashed potato base with a smooth and fluffy texture, topped with a layer of golden-brown caramelized onions that have a slightly glossy and soft appearance. The onions are spread unevenly on the top, creating a contrast between the light potato layer and the deeper, rich brown color of the onions. The background features a white marbled texture. Photo taken with an iphone --ar 2:3 --v 7 - French Onion Mashed Potatoes, caramelized onion mashed potatoes, creamy onion mashed potatoes, gourmet mashed potato sides, cheesy onion mashed potatoes

Ingredients You’ll Need

The magic here happens by layering simple ingredients that bring out the best flavors in each other. I like to choose sweet onions for caramelizing because they mellow out beautifully, and Yukon Gold potatoes create that perfect creamy texture without getting gluey.

Flat lay of thinly sliced golden sweet onions with rich amber caramelized edges, whole russet and Yukon gold potatoes showing their creamy yellow and light brown skins, several cubes of pale yellow unsalted butter, a small mound of freshly grated pale ivory Gruyere cheese with a slightly crumbly texture, a glass container of thick white heavy cream, and a few sprigs of fresh green herbs scattered naturally, all arranged with soft natural light highlighting the warm colors and varied textures, placed on white marbled surface, photo taken with an iphone --ar 2:3 --v 7 - French Onion Mashed Potatoes, caramelized onion mashed potatoes, creamy onion mashed potatoes, gourmet mashed potato sides, cheesy onion mashed potatoes

Caramelized onions: Using thinly sliced sweet onions helps achieve that lovely golden color and natural sweetness during slow cooking.
Unsalted butter: I always recommend unsalted so you can control the seasoning perfectly.
Kosher salt: Essential for seasoning both the onions and the potatoes well without overpowering.
Potatoes: Russet or Yukon Gold are your best bet; Russet for fluffy texture, Yukon Gold for creamier, buttery results.
Heavy whipping cream: Warming this with butter before adding keeps the potatoes creamy and rich.
Gruyère cheese: Freshly grated for a nutty, melty touch that elevates the whole dish.
Freshly ground black pepper: Just a pinch to finish off and balance the flavors.

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Note: You’ll find the complete list of ingredients, along with their exact measurements, in the printable recipe card at the bottom of this post.

Variations

One of the things I love most about this French Onion Mashed Potatoes Recipe is how easily you can tweak it to your liking. Whether you’re avoiding dairy or want a bit more crunch, you can adjust it to fit your meal perfectly.

Dairy-Free Variation: Replace butter and cream with olive oil and coconut milk or your favorite plant-based alternatives—I tried this for a friend, and it turned out surprisingly delicious!
Herb Infusion: Stir in some fresh thyme or rosemary during the caramelization step for an herbaceous twist.
Extra Cheesy: Swap Gruyère for sharp aged cheddar or add a sprinkle of Parmesan on top for a bolder flavor.
Crispy Onion Topping: Fry some thinly sliced onions separately and sprinkle over the mashed potatoes just before serving for added texture.

How to Make French Onion Mashed Potatoes Recipe

Step 1: Slowly Caramelize Your Onions for That Deep Flavor

Heat 6 tablespoons of unsalted butter in a skillet over medium-low heat, then toss in the thinly sliced sweet onions with a generous pinch of kosher salt. I like to stir them every few minutes to make sure they don’t stick or burn. After about 10 to 15 minutes, turn the heat down to low—we want slow, patient cooking so the onions turn golden and sweet without burning. Expect this to take about 45 to 60 minutes. It’s a bit of a slow dance, but I promise—it’s worth the wait!

Step 2: Prep and Cook Your Potatoes Just Right

I always recommend prepping your potatoes ahead if you can—peel, chop, and soak them in cold water to remove excess starch, storing in the fridge up to 18 hours before cooking. When you’re ready, drain and put the chunks in a pot with cold, salted water. Bring it to a boil over medium heat, then simmer until fork-tender, about 12 to 15 minutes. Watch them closely—if your pieces are smaller, check at 10 minutes to avoid overcooking.

Step 3: Warm Your Butter and Cream While Potatoes Boil

While the potatoes are cooking, heat 12 tablespoons of butter with 1½ cups of heavy whipping cream over medium-low heat. This warm mixture helps your mashed potatoes stay creamy and ultra smooth—don’t skip this step! It’s one of my small secrets for rich results every time.

Step 4: Mash, Mix, and Fold in That Wonderful Onion Flavor

Drain your potatoes well and get ready to mash. I use a potato masher first to get the consistency I like. Then, mix in half of your warm butter and cream, plus 1 teaspoon salt, tasting as you go. If you like ultra-smooth potatoes, a hand mixer set to low helps, but be careful not to overmix or they’ll turn gummy. Finally, stir in the grated Gruyère and the other half of your caramelized onions, allowing the cheese to melt slowly into the mixture. Season with extra salt and pepper as needed—tasting frequently is key here.

Step 5: Serve with Style and Extra Onion Love

Spoon the creamy potatoes onto your serving dish and top with the remaining caramelized onions. The contrast in texture and that gorgeous onion aroma will have everyone coming back for seconds!

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Pro Tips for Making French Onion Mashed Potatoes Recipe

Go Low and Slow with Onions: Patience here makes all the difference. Rushing caramelization results in bitter onions, so keep the heat low.
Soak Potatoes to Remove Starch: I learned this trick to get fluffy potatoes instead of gluey ones—soaking before cooking helps immensely.
Warm Your Butter and Cream: Adding warm dairy to the potatoes keeps them creamy and blends beautifully, no lumps.
Avoid Overmixing: Excessive mixing makes potatoes gummy. Use gentle mashing or a low-speed mixer.

How to Serve French Onion Mashed Potatoes Recipe

A white bowl filled with creamy mashed potatoes forms the base layer, with a smooth, thick texture. Swirled on top are golden brown caramelized onions, scattered unevenly in rich, glossy patches that follow the curves of the mashed potatoes, adding contrast with their shiny, slightly crispy look. The bowl sits on a white marbled surface, lending a clean and bright background to the warm, comforting dish. photo taken with an iphone --ar 2:3 --v 7 - French Onion Mashed Potatoes, caramelized onion mashed potatoes, creamy onion mashed potatoes, gourmet mashed potato sides, cheesy onion mashed potatoes

Garnishes

I always finish with a sprinkle of fresh chives or parsley for color and a little fresh bite that cuts through the richness. Sometimes a small grating of nutmeg or extra cracked black pepper on top adds a lovely aroma too. And if you’re feeling indulgent, an extra handful of crispy fried onions is pure heaven.

Side Dishes

This French Onion Mashed Potatoes Recipe pairs beautifully with roasted chicken, grilled steak, or even a simple green vegetable like sautéed green beans or roasted Brussels sprouts. My family goes crazy when I serve this alongside a garlic-rubbed roast beef—it’s just perfect!

Creative Ways to Present

For special occasions, I sometimes pipe the mashed potatoes into little rosettes on a baking sheet and pop them under the broiler until golden on top, adding caramelized onion bits before serving. It looks fancy but is surprisingly easy to pull off!

Make Ahead and Storage

Storing Leftovers

I store leftovers in an airtight container in the fridge, where they keep well for up to 3 days. To keep the texture smooth, I recommend gently reheating and adding a splash of cream or milk to loosen them up before serving.

Freezing

I used to struggle freezing mashed potatoes because they often got dry or grainy. With this recipe’s high butter and cream content, I found it freezes quite well if you cool them fully and seal them tightly. Defrost overnight in the fridge before reheating gently.

Reheating

When reheating, use a low heat on the stovetop or in the microwave in short bursts, stirring often. If the potatoes feel thick, stir in a bit of warm cream or milk to reach that perfect creamy texture again.

FAQs

Can I use regular yellow onions instead of sweet onions for the caramelized onions?

Absolutely! Yellow onions work well for caramelizing and will offer a slightly sharper taste compared to sweet onions, but the slow cooking process mellows them nicely. Just be sure to caramelize slowly over low heat to avoid bitterness.
What is the best potato to use in this French Onion Mashed Potatoes Recipe?

Russet potatoes are great for fluffy, light mashed potatoes, while Yukon Golds bring a naturally buttery and creamier texture. I personally prefer Yukon Golds for this recipe because they complement the rich, cheesy flavors perfectly.
Can I make the caramelized onions ahead of time?

Yes, caramelized onions keep beautifully in the fridge for up to a week. Making them in advance saves you time on the day you prepare the mashed potatoes. Just warm them a bit before folding into the potatoes for best flavor.
Is it okay to use a hand mixer to mash the potatoes?

You can, but use it on a low speed and only briefly. Overmixing with an electric mixer can make mashed potatoes gluey or gummy, so I suggest mashing by hand first and then smoothing out with the mixer just a little if you want extra creaminess.
How do I adjust the salt in this recipe?

Salt amounts can vary depending on your taste and the saltiness of your butter or cheese. I always recommend adding salt gradually, tasting as you go, especially after adding the caramelized onions and cheese, to avoid oversalting. It’s easier to add more than to fix too much salt.

Final Thoughts

This French Onion Mashed Potatoes Recipe is one of those dishes that feels like an indulgent hug on a plate. I remember making it for my family the first time and getting so many compliments that it quickly became a holiday staple. The blend of creamy potatoes, sweet onions, and melted Gruyère creates a comforting yet elegant dish that’s perfect any time you want to impress without a ton of fuss. Give it a go—I promise it’ll become one of your favorite mashed potato recipes too!