Buttery, creamy, and cheesy with decadent caramelized onions, these French Onion Mashed Potatoes are such a fun twist on regular mashed potatoes! Regular mashed potatoes probably won't feel as exciting after trying this comforting mashup of two beloved classic foods!
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These elegant and hearty mashed potatoes can certainly be the star side dish, but they also play well with company! They work particularly well with rich and tender slow-roasted meats, like this apple cider pork roast, this slow cooker sirloin tip roast, or this Dutch oven pot roast.
Deeply savory, creamy, buttery, plus a little bit nutty from the cheese and sweet from those deeply caramelized onions, what's not to love?!
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Why We Love This Recipe
- Made with just a few ingredients. You really don't need much to get these delicious potatoes going, just a little bit of patience with the caramelized onions. This recipe uses standard ingredients available at any grocery store.
- Elegant but easy. Yes, these are certainly refined in flavor, but they are also so simple to prepare. Anyone can make these!
- Super versatile. They are mashed potatoes after all, and they have a lot of friends! Make a big batch and reheat it with dinner all week. Or, let them shine at the dinner party, Thanksgiving, or any holiday dinner.
🥔Ingredients
Here are the ingredients we used for this recipe. You can find more information on substitutions below.
- Potatoes. Any potato of your choosing works here. We used red skin potatoes because that's what we had on hand, and they do work quite well, especially if serving with a heartier dish like a pot roast. We also love red skin mashed potatoes because we don't have to peel them. 😂Yukon golds or Russet potatoes make a more classic "fluffy" mashed potato, so just use what you like!
- Butter. We recommend using unsalted, if possible, so you have complete control over the amount of salt that goes in the dish. We also recommend using a high-quality, European-style butter if possible! The higher fat content and rich creamy texture, and flavor will make a big difference in flavor. Butter is a main ingredient and flavor enhancer in this dish. Plugrà is our favorite! 🫶🏼🫶🏾
- Onions. Sweet yellow onions or Vidalia onions, sliced thin and as uniform as possible.
- Garlic. Fresh is going to taste the best, if possible.
- Kosher salt. We use Diamond Crystal salt in all of our recipes. It dissolves really well because of the pyramid-like shape. The faster it dissolves, the easier it is to taste and adjust to suit your preferences. This article goes into more depth about why we prefer it!
- Worcestershire sauce. Adds lots of savory and umami flavor and depth to the onions.
- Balsamic vinegar. Adds a lovely hint of rich, sweet acidity and body to the onions.
- Sugar. To sweeten up the onions a little more!
- Thyme. Optional, but very delicious. We just add a few whole sprigs to the onions when they are caramelizing to infuse them with flavor, then discard them before serving.
- Heavy cream. For a really rich, creamy mashed potato.
- Gruyerè cheese. We grate it fresh so it melts into the potatoes really nicely. You can use Swiss cheese instead. Avoid pre-shredded cheeses if possible, because they often have anti-caking agents added that prevent a great melt.
Visit the recipe card for the full quantities and nutritional information.
✨Substitutions & Variations
- Add red wine or beef stock. For even more French onion soup flavor, you can add beef broth or red wine along with the onions. Start with about ¼ cup, and add up to ½ cup if needed to deglaze the pan. The onions may need a bit more time to simmer and cook off the excess liquid, but it will also help prevent the onions from burning!
- Lighter. You can swap the heavy cream for half and half to still get a rich and creamy potato that is slightly lightened up! Milk is also an option, but we strongly suggest using half and half or cream instead for the richest, creamiest texture. Either way, these potatoes will still be delicious!
This recipe hasn't been tested with any other substitutions or variations, so we can't guarantee any results. If you make a change, let us know how it goes in the comments below!
🔪Prep Work
- Slice the onions into thin strips.
- Mince garlic.
- Peel (if needed), remove any blemishes, and cut potatoes into roughly equal-sized pieces. We tend to cut red-skinned potatoes in half, thirds, or quarters. We aim for larger chunks, so that the potatoes don't get waterlogged or mushy. Cutting potatoes really small allows them to absorb more water, and what we want them to absorb is cream and butter!
- Heat a large skillet over medium-low heat.
- Measure out remaining ingredients.
Instructions
- Step 1: Heat the butter in a skillet over medium-low heat. Add the onions with a big pinch of salt. Cook for 10 minutes, stirring often, so the onions begin to cook down
- Step 2: Add in fresh thyme sprigs, garlic, sugar, Worcestershire, and balsamic, and stir for about 1 minute, then reduce the heat to low.
- Step 3: Continue to cook, stirring occasionally, until the onions are golden and caramelized, about 45 to 60 more minutes. You can't rush it!
Pro Tip
If the onions begin to burn or stick, add a splash of liquid. Water, broth, or wine all work perfectly fine.
- Step 4: Place the potatoes in a large pot of cold water over medium heat. Season the water with lots of salt (about 1 tablespoon per pound of potatoes!) Bring the potatoes to a boil, then boil until they are fork-tender, about 13 to 15 minutes. (If your potato chunks are smaller, check after 10 minutes.)
- Step 5: Drain the water from the potatoes, then add them back to the Dutch oven over medium-low heat and stir occasionally for 3-5 minutes. All of the steam coming off of the potatoes is good, this means less water in the potatoes, and ensures the potatoes can soak up more cream and butter!
- Step 6: While the potatoes are drying off in the Dutch oven, heat the butter and cream in a small saucepan over medium-low heat until the mixture is warmed through.
- Step 7: Mash the potatoes by hand, and stir in the hot cream and butter mixture as needed. Incorporate the shredded cheese while the potatoes are still warm so they can melt properly.
Pro Tip
We recommend mashing the potatoes by hand to avoid overmashing! Overmashing the potatoes can lead to a sticky, gluey consistency.
- Step 8: Stir in about half of the caramelized onions, reserving more for serving. Taste, then add salt and pepper.
- Step 9: Top the potatoes with the remaining caramelized onions, more melted butter if desired, and fresh thyme. Enjoy!
If you have lots of leftover gruyere cheese from this recipe, turn it into dinner with this French onion soup pot roast!
Storage
Fridge Storage
Store leftovers in an airtight container in the fridge for up to 5 days. Reheat gently in the microwave. We don't recommend freezing these potatoes.
Make Ahead Tips
Prepping for guests? Prep ahead to save yourself some stress! Start with the caramelized onions as they take the most time.
We love serving these potatoes with this delicious apple cider pork!
Caramelized Onion Expert Tips
- Start with the right onions. Sweet onions (Vidalia, Walla Walla, or Maui) have more natural sugar and caramelize beautifully with less bitterness. Yellow onions work well, too. Avoid red onions-they can be too sharp or become an unappealing red-grey color.
- Slice uniformly. Slice onions thinly and consistently (about ¼ inch thick) so they cook evenly. Uneven slices mean some pieces burn while others don't cook properly.
- Don't rush the process. True caramelization takes 45-60 minutes. If a recipe claims "caramelized onions in 10 minutes," you can't trust it; there's no such thing as a "quick" caramelized onion! Low and slow is the only way to develop deep, sweet, complex flavor, so be patient.
- Deglaze if needed. If the onions start to stick or develop brown bits on the bottom of the pan, add a tablespoon of water, wine, or broth, and scrape up those browned bits. This is just flavor! However, you don't want anything to burn, so keep a close eye on them.
Mashed Potato Expert Tips
- Salt the cooking water generously. This is your only chance to season the potatoes from the inside. You want about 1 tablespoon of kosher salt per pound of potatoes, don't be shy!
- Start with cold water. Place potatoes in cold water, then bring to a boil. This ensures even cooking. If you add potatoes to already-boiling water, the outside cooks faster than the inside.
- Don't overcook the potatoes. Boil just until fork-tender (a fork slides in easily, but the potato doesn't fall apart). Overcooked potatoes absorb too much water and become mushy. Check after 10-12 minutes if your chunks are on the smaller side.
- Drain the potatoes and dry again in the Dutch oven. After draining, return the potatoes to the hot pot over low heat for a few minutes. This allows excess moisture to evaporate, resulting in fluffier, less watery potatoes.
- Heat your cream and butter. Cold dairy will cool down your potatoes and make them harder to mash smoothly.
- Mash by hand. Use a potato masher to avoid over-mashing. Don't use a food processor, immersion blender, or electric mixer. This will overwork the starches and create gluey, gummy potatoes.
- Add dairy gradually. Start with about half the cream and butter mixture, mash until combined, then add more as needed. You can always add more liquid, but you can't take it away.
- Fold in cheese while the potatoes are hot. Add the cheese while the potatoes are still hot so it melts smoothly and incorporates evenly. Cold cheese won't melt properly and will leave clumps.
- Taste and adjust. Mashed potatoes need more salt than you think. Taste after mixing in the onions and cheese, then add salt and pepper gradually until they're seasoned just how you like!
💬Common Questions
Can I caramelize onions quickly?
Unfortunately, no. You have to take it low and slow, that's the only way to develop those rich, sweet flavors.
Why are my mashed potatoes gluey? Can I fix it?
More than likely, you either overworked them or overcooked them. This can release too much starch. Avoid this by not overcooking them and by mashing by hand to avoid overworking them!
If the damage is already done, simply add melted butter (about 1 tablespoon at a time) and mix gently with a rubber spatula until the texture improves.
🍴Pairing
There's no shortage of delicious meals to serve these potatoes with! Here are some of our favorites!
More Recipes To Try
Looking for more delicious and decadent sides? Try these!
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📖 Recipe
French Onion Mashed Potatoes
These French Onion Mashed Potatoes are the ultimate mashup of two beloved comfort food dishes! These potatoes are super buttery, creamy, and cheesy with nutty Gruyere cheese and decadent caramelized onions. This elegant side dish is truly a star, but also allows main dishes to shine!
Ingredients
Caramelized onions
- ¼ cup unsalted butter 1 stick
- 5 medium sweet onions thinly sliced
- ½ teaspoon kosher salt
- 6 cloves garlic minced
- 1 tablespoon balsamic vinegar
- 1 tablespoon Worcestershire sauce
- 1 tablespoon sugar
Potatoes
- 6 pounds potatoes cut into roughly even sized chunks (not too small or they will soak up too much water)
- ¾ cup unsalted butter 3 sticks
- 3 cups cream
- 6 ounces gruyere cheese
- 1 ½ teaspoons black pepper to taste
- 4-5 teaspoons kosher salt
Instructions
Caramelized onions
- Heat the butter in a skillet over medium-low heat. Add the onions with a big pinch of salt. Cook for 10 minutes, stirring often, so the onions begin to cook down.¼ cup unsalted butter, 5 medium sweet onions, ½ teaspoon kosher salt
- Add in fresh thyme sprigs, garlic, sugar, Worcestershire sauce, and balsamic, and stir for about 1 minute, then reduce the heat to low.6 cloves garlic, 1 tablespoon balsamic vinegar, 1 tablespoon Worcestershire sauce, 1 tablespoon sugar
- Continue to cook, stirring occasionally, until the onions are golden and caramelized, about 45 to 60 more minutes. You can't speed this process up!
Potatoes
- Meanwhile, llace the potatoes in a large pot of cold water over medium heat. Season the water with roughly 1 tablespoon of kosher salt per pound of potatoes. Bring the potatoes to a boil, then boil until they are fork tender, about 13 to 15 minutes. (If your potato chunks are smaller, check after 10 minutes.)6 pounds potatoes
- While the potatoes are boiling, heat the butter and cream in a saucepan over medium-low heat until the mixture is warmed through.¾ cup unsalted butter, 3 cups cream
- Mash the potatoes by hand to avoid overmixing, stir in the cream and butter mixture, don't over mash the potatoes, mixing in the cheese simultaneously while the potatoes are warm to ensure the cheese melts.6 ounces gruyere cheese
- Stir in about half of the caramelized onions, reserving more for serving. Taste, then add salt and pepper.1 ½ teaspoons black pepper, 4-5 teaspoons kosher salt
- Serve with more butter, salt, pepper, and fresh thyme. Enjoy!
Save This Recipe! 💌
We'll email this post to you, so you can come back to it later!
Notes
Caramelized onion tips
- Start with the right onions. Sweet onions (Vidalia, Walla Walla, or Maui) have more natural sugar and caramelize beautifully with less bitterness. Yellow onions work well, too. Avoid red onions-they can be too sharp or become an unappealing red-grey color.
- Slice uniformly. Slice onions thinly and consistently (about ¼ inch thick) so they cook evenly. Uneven slices mean some pieces burn while others don't cook properly.
- Don't rush the process. True caramelization takes 45-60 minutes. If a recipe claims "caramelized onions in 10 minutes," you can't trust it; there's no such thing as a "quick" caramelized onion! Low and slow is the only way to develop deep, sweet, complex flavor, so be patient.
- Deglaze if needed. If the onions start to stick or develop brown bits on the bottom of the pan, add a tablespoon of water, wine, or broth, and scrape up those browned bits. This is just flavor! However, you don't want anything to burn, so keep a close eye on them.
Mashed potato tips
- Salt the cooking water generously. This is your only chance to season the potatoes from the inside. You want about 1 tablespoon of kosher salt per pound of potatoes, don't be shy!
- Start with cold water. Place potatoes in cold water, then bring to a boil. This ensures even cooking. If you add potatoes to already-boiling water, the outside cooks faster than the inside.
- Don't overcook the potatoes. Boil just until fork-tender (a fork slides in easily, but the potato doesn't fall apart). Overcooked potatoes absorb too much water and become mushy. Check after 10-12 minutes if your chunks are on the smaller side.
- Drain the potatoes and dry again in the Dutch oven. After draining, return the potatoes to the hot pot over low heat for a few minutes. This allows excess moisture to evaporate, resulting in fluffier, less watery potatoes.
- Heat your cream and butter. Cold dairy will cool down your potatoes and make them harder to mash smoothly.
- Mash by hand. Use a potato masher to avoid over-mashing. Don't use a food processor, immersion blender, or electric mixer. This will overwork the starches and create gluey, gummy potatoes.
- Add dairy gradually. Start with about half the cream and butter mixture, mash until combined, then add more as needed. You can always add more liquid, but you can't take it away.
- Fold in cheese while the potatoes are hot. Add the cheese while the potatoes are still hot so it melts smoothly and incorporates evenly. Cold cheese won't melt properly and will leave clumps.
- Taste and adjust. Mashed potatoes need more salt than you think. Taste after mixing in the onions and cheese, then add salt and pepper gradually until they're seasoned just how you like!
Nutrition
Calories: 563kcalCarbohydrates: 46gProtein: 10gFat: 39gSaturated Fat: 24gPolyunsaturated Fat: 2gMonounsaturated Fat: 10gTrans Fat: 1gCholesterol: 114mgSodium: 888mgPotassium: 1041mgFiber: 5gSugar: 10gVitamin A: 1376IUVitamin C: 45mgCalcium: 214mgIron: 2mg
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Anne Olson says
I made these with the apple cider pork roast as recommended and WOW! what a blast of flavor and I will be making these again.
Wonderful recipe!
Briana says
Anne you truly made our day with these amazing comments!! We're SO glad you loved the potatoes so much! Thank you again for all of your kind and encouraging words, readers like you really make it all worth it! 🙂