Oh, mashed potatoes! Just saying the words brings a smile to my face. They’re pure comfort food, aren’t they? But let me tell you, taking them from “good” to “OMG, what is THIS?!” is ridiculously easy. My secret? Caramelized Onion Mashed Potatoes. Yep, those sweet, deeply savory caramelized onions just melt into creamy, dreamy mashed potatoes, turning a classic side dish into something truly special. I remember making these for a potluck years ago, and people were practically fighting over the last scoop! It’s my go-to for making any meal feel like a celebration, proving that simple ingredients can create something absolutely magical with just a little patience.

Why You’ll Love These Caramelized Onion Mashed Potatoes
Trust me, you’re going to want to make a double batch of these beauties. Here’s why:
- Super Easy Flavor Bomb: Honestly, the hardest part is waiting for those onions to caramelize. Everything else is a breeze!
- Unbeatable Taste: That sweet, savory onion goodness mixed with creamy potatoes? It’s pure culinary magic in every bite!
- Dinner Party Darling: These mashed potatoes are fancy enough for guests but cozy enough for a Tuesday night. They just make everything better.
- Pure Comfort: It’s your favorite classic, but with a gourmet twist that everyone raves about.

Ingredients for the Best Caramelized Onion Mashed Potatoes
Alright, let’s talk ingredients! Because these humble spuds and onions are about to do some serious work in your kitchen. I always make sure to grab good quality stuff for this recipe.
For the Potatoes:
- 2 lbs Yukon Gold potatoes: These are my absolute favorite for mashing! They’re buttery and creamy and don’t get gluey like some other types. Make sure they’re peeled and cut into big chunks – about quartered so they cook evenly.
- 1/2 cup milk: I like to warm mine up a bit, it makes for smoother potatoes. Whole milk gives the best richness, but 2% works too!
- 4 tbsp unsalted butter: Butter makes everything better, right? Unsalted lets you control the saltiness perfectly.
- 1 tsp salt (or to taste): Start with this, and you can always add more.
- 1/2 tsp black pepper (or to taste): Freshly ground is best if you have it!
For the Caramelized Onions:
- 2 large yellow onions: These are the sweethearts of the dish! Slice them nice and thin so they cook down beautifully.
- 1 tbsp olive oil: Just a little to get things started.
- 1 tbsp unsalted butter: Adds a touch more richness to the onions as they cook.

Equipment Needed for Caramelized Onion Mashed Potatoes
You don’t need a fancy kitchen for this one, just a few trusty tools! Here’s what you’ll want to have handy:
- A big pot: This is for boiling your potatoes until they’re perfectly tender.
- A good skillet: Your workhorse for slowly, beautifully caramelizing those onions.
- A potato masher: Your best friend for getting those creamy mashed potato vibes.
Step-by-Step Guide to Making Caramelized Onion Mashed Potatoes
Okay, so making these glorious Caramelized Onion Mashed Potatoes is really pretty simple when you break it down. It’s all about doing a couple of things at the same time, and a little bit of patience goes a long way, especially with those onions turning golden and sweet! You’ve got this!
Cooking the Potatoes
First things first, let’s get those potatoes going. Pop your peeled and quartered Yukon Golds into that big pot. Cover them with cold water – this helps them cook more evenly. A nice pinch of salt in that water is crucial for flavor from the start. Bring it all to a rolling boil, then let them bubble away for about 15-20 minutes. You’ll know they’re ready when you can easily stab ’em with a fork – they should be super tender! If you love potatoes, you might also want to check out these Garlic Herb Roasted Potatoes.
Caramelizing the Onions to Perfection
While your potatoes are happily boiling, let’s tackle those onions. Grab your skillet and set it over medium-low heat. Add that olive oil and butter, letting it get warm. Now, toss in your thinly sliced onions. The key here is low and slow. You want to stir them every so often, letting them soften and turn that gorgeous deep golden-brown color. This can take anywhere from 30 to 40 minutes, but oh, the smell! Season them with a bit of salt and pepper as they cook. This step is where all that magic sweetness happens!
Mashing and Mixing the Potatoes
Drain those tender potatoes like a pro! Get all the water out. Pop them back into the warm, empty pot – this helps evaporate any extra moisture. Now, grab your trusty potato masher and get to work. Mash them up until they’re mostly smooth, but don’t go crazy and make them paste-like. Add in your warmed milk and that glorious butter. Stir it all around until the butter melts and everything is creamy and luscious. Taste it now and add more salt and pepper if you think it needs it – this is your moment!
Combining and Serving Your Caramelized Onion Mashed Potatoes
Almost there! Gently, and I mean gently, fold those sweet, caramelized onions into your fluffy mashed potatoes. You don’t want to mash them totally out of existence; a little bit of texture is lovely. Give it one last gentle stir to distribute them evenly. And voilà! Serve these beauties piping hot. They’re best enjoyed right away when they’re warm, creamy, and utterly irresistible.

Tips for the Ultimate Caramelized Onion Mashed Potatoes
You know, I’ve made these Caramelized Onion Mashed Potatoes more times than I can count, and I’ve picked up a few little tricks that really make them extra special. Don’t skip these if you want pure potato perfection!
First, please, please don’t rush those onions. Seriously, low and slow is the only way to go. If you crank up the heat, they’ll just burn instead of sweetly caramelizing. Patience is your secret ingredient here! Also, for an extra layer of richness, try using half milk and half heavy cream when you’re mixing the potatoes. It makes them unbelievably decadent, almost like a creamy gratin, but in mashed potato form!
Ingredient Notes and Substitutions
Okay, so let’s chat about a couple of little things in this recipe that make a big difference, and what you can do if you’re missing something. When I make my Caramelized Onion Mashed Potatoes, I swear by Yukon Gold spuds. They’re just naturally buttery and have this amazing creamy texture that doesn’t turn gummy. If you absolutely can’t find them, Russets will work in a pinch, but you might need to mash them a *tiny* bit more gently. For the milk, whole milk gives you that super rich, comforting flavor that I love. If you’re out, 2% is fine, or even a splash of half-and-half will make them extra decadent! And butter? Always unsalted so you can control the saltiness yourself. Margarine just doesn’t give you that same depth of flavor, trust me on this one!
Serving Suggestions for Caramelized Onion Mashed Potatoes
These Caramelized Onion Mashed Potatoes are so versatile, they honestly make almost any meal better! They’re especially fantastic alongside rich roasts like this Jalapeno Glazed Pork Tenderloin, or with something a little more elegant, like this Marry Me Chicken. They’re also perfect with a hearty steak or even a simple pan-seared salmon. Honestly, anything that needs a creamy, savory side dish will be elevated by these onions!
Storage and Reheating Instructions
Leftovers of these amazing Caramelized Onion Mashed Potatoes? Lucky you! Store any extra in an airtight container in the fridge for up to 3 days. When you’re ready to reheat, I find the stovetop is best. Gently warm them in a pot over low heat, stirring frequently and adding a splash more milk or butter if they seem a little dry. You can also do this in the microwave, just give them a good stir halfway through. Avoid the oven if you can, as they can dry out a bit.
Frequently Asked Questions about Caramelized Onion Mashed Potatoes
Got questions about these amazing mashed potatoes? I’ve got you covered! Let’s dive into some common queries about making the best Caramelized Onion Mashed Potatoes ever.
Can I make the caramelized onions ahead of time?
Absolutely! This is actually my go-to trick. Caramelized onions hold up beautifully in the fridge for about 3-4 days. Just store them in an airtight container. Then, when you’re ready to make your mashed potatoes, just gently warm them up before folding them in. It makes weeknight dinners so much easier!
What kind of potatoes are best for mashed potatoes?
For the absolute creamiest texture, I’m a huge fan of Yukon Gold potatoes. They have a naturally buttery flavor and a great creamy consistency that doesn’t get gluey. Russets can work too, but you have to be a bit more careful not to over-mash them. Just make sure you peel them and cut them into even-sized chunks!
How do I prevent my mashed potatoes from being gummy?
Oh, the dreaded gummy mashed potato! To avoid this disaster, the key is really not to overwork them. Mash them just until they’re mostly smooth, then gently fold in your liquids and butter. Also, make sure you drain your potatoes really well after boiling, and returning them to the hot, dry pot for a minute helps steam off any extra moisture. Don’t use a food processor – that’s a sure way to get gummy potatoes!
Can I add garlic to these mashed potatoes?
Yes, you totally can! If you love garlic, I recommend roasting a few cloves of garlic until they’re soft and sweet, then mashing them right in with your potatoes. You could also sauté some minced garlic for a minute in the skillet with the onions before caramelizing them. Just a little heads-up, garlic can sometimes overpower the delicate sweetness of the onions, so use it wisely!
Nutritional Information (Estimated)
Just a heads-up, these numbers are just a ballpark! What you see here is an estimate per serving for my Caramelized Onion Mashed Potatoes, and things can change a bit depending on exactly what you use – like the brand of butter or the type of milk. But it gives you a good idea!
- Calories: Approx. 300-350
- Fat: Approx. 15-20g
- Saturated Fat: Approx. 8-10g
- Protein: Approx. 5-7g
- Carbohydrates: Approx. 35-45g

Caramelized Onion Mashed Potatoes
Ingredients
Equipment
Method
- Place the quartered potatoes in a large pot and cover with cold water. Add a pinch of salt. Bring to a boil and cook for 15-20 minutes, or until fork-tender.
- While the potatoes are cooking, heat the olive oil and butter in a skillet over medium-low heat. Add the sliced onions and cook slowly, stirring occasionally, for 30-40 minutes, or until deeply caramelized and sweet. Season with salt and pepper.
- Drain the cooked potatoes well. Return them to the hot, empty pot. Mash the potatoes with a potato masher until mostly smooth.
- Add the warmed milk and 4 tablespoons of butter to the mashed potatoes. Stir until the butter is melted and the potatoes are creamy. Season with salt and pepper to taste.
- Gently fold in the caramelized onions. Serve hot.