Best Caramelized Onion Mashed Potatoes

Take your usual mashed potatoes up a notch with these Caramelized Onion Mashed Potatoes! Slow-cooked, golden onions are mixed into creamy Yukon gold potatoes for a rich, savory, and slightly sweet side that’s guaranteed to steal the show. They’re perfect with roasted meats, veggies, or as part of your holiday spread!

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large bowl filled with mashed potatoes, topped with green herbs and caramelized onions.

Why This Recipe Works

You’ve never tasted a combination as cozy and irresistible as caramelized onions and mashed potatoes. That’s why these caramelized onion mashed potatoes deserve a spot at your next family dinner, holiday feast, or potluck!

Red onions are cooked low and slow until deeply golden, then brightened with a splash of red wine and balsamic vinegar. Folded into creamy Yukon gold mashed potatoes, they create a rich and savory side dish that might just outshine the main course. Pair it with beef ragu, prime rib roast, or even simple baked chicken breasts, and watch it disappear from plates.

The real beauty of these potatoes is their versatility—add bacon, cheese, or roasted garlic for even more flavor. And if you don’t feel like making a fresh batch of potatoes, you can use the leftovers already in your fridge or make some easy mashed potatoes ahead of time. The caramelized onions are enough to jazz up any mashed spuds!

Ingredients

Red Onions: Caramelized onions are cooked low and slow until they become a deep golden brown color.
Olive Oil: Used to sauté the onions, giving them a rich, glossy texture as they caramelize. Choose a high-quality extra-virgin olive oil for the best flavor.
Red Wine: Wine pairs exceptionally well with red onions!
Balsamic Winegar: For brightness and tang. Use a high-quality D.O.P. balsamic vinegar for the best results.
Yukon Gold Potatoes: These are always my go-to for creamy, buttery mashed potatoes. To lower the carbs in this recipe, make a cauliflower mash instead.
Bay Leaves: I like to add a bay leaf or two to the boiling potatoes for a subtle, earthy note. Be sure to remove the bay leaves before mashing.
Butter: No mashed potato recipe is complete without butter! We’ll add it to both the potatoes and the caramelized onions for an extra layer of rich, luxurious flavor.
Cream: You’ll need heavy cream and sour cream to smooth out those mashed potatoes.

small white bowls filled with butter, dark liquids, and milk next to potatoes and onions.

Instructions

Caramelize the Onions: Heat olive oil and butter in a large skillet over low heat. Add the onions and salt and cook until they’re soft and browned.
Add Wine & Balsamic: Increase the heat, pour the red wine and balsamic vinegar into the skillet, and simmer until the wine evaporates. At this point, the onions should be very soft and caramelized. Season with more salt if needed and set aside.
Cook the Potatoes: In a small saucepan, gently warm the cream and butter until the butter is melted. Boil the potatoes and bay leaves in a pot of salted water. Drain when they’re fork-tender, then mash them up.
Assemble the Mash: Add your warm cream and butter mixture and the sour cream to the pot with the potatoes. Mash until the potatoes are smooth. To finish, stir in the caramelized onions, then top with fresh dill. Serve while hot.

stirring mashed potatoes in a metal pot.

Substitutions & Variations

Red Onions: If you don’t have red onions, sweet onions, white onions, yellow onions, shallots, or even leeks will work beautifully.
Red Wine: If you don’t want to use alcohol in this recipe, omit the red wine or replace it with beef or vegetable broth.
Balsamic: No balsamic on hand? Try red wine vinegar for a tangier alternative.
Dairy-Free: If you need to accommodate any vegans, substitute heavy cream and butter with coconut cream and olive oil.
Different Herbs: Replace fresh dill with chives or parsley for a herbal twist.
Cheesy: Mix in grated Parmesan, gruyere, or cheddar cheese for added richness.
Add More Flavor: Stir in 2 or 3 minced cloves of garlic, a head of roasted garlic, a pinch of smoked paprika, or a sprinkle of crispy bacon bits.

Storing & Reheating

Great news! Caramelized onion mashed potatoes store well and can be easily reheated for all your future side dish needs. Just follow these guidelines:

Fridge: Transfer cooled leftovers to an airtight container and store them in the fridge for up to 3-4 days.
Freezer: Once they have cooled, you can freeze the potatoes in a freezer-safe container for up to 2-3 months.
Reheating: Gently reheat your potatoes on the stovetop over low, stirring occasionally, or in the microwave, adding a splash of cream to restore their light, creamy texture.

large metal pot filled with mashed potatoes next to a bowls with more mashed potatoes and caramelized onions.

Expert Tips

Slice Onions Evenly: Uniform onion slices ensure even caramelization and consistent flavor throughout.
Stir the Onions: Remember to stir the onions often so they don’t burn. The longer you let them caramelize, the richer the flavors will be!
Deglaze the Pan: If the skillet with the onions becomes dry, add a small splash of water to deglaze it and continue cooking.
Warm Your Ingredients: Adding warm cream and butter helps to keep the potatoes hot and achieve a smoother texture.

FAQs

What kind of potatoes are best for mashed potatoes?

Yukon Golds are perfect for mashing because they’re naturally starchy and creamy. Red potatoes or Russets are also great choices if you don’t have any Yukon Golds.

Do you have to peel potatoes before mashing them?

It’s up to you! Leaving the peels on will give the mashed potatoes a little more texture. If you prefer ultra-smooth mashed potatoes, peel them ahead of time.

Can this be made ahead of time?

The caramelized onions can be made up to 3 days in advance and kept in an airtight container in the fridge. The mashed potatoes can be made and kept in the fridge for 2 to 3 days before serving.

womans hands using a spoon to scoop mashed potatoes out of a large pink bowl.

If you enjoyed this caramelized onion mashed potatoes recipe, be sure to check out some more potato favorites like these:

Did you try these Caramelized Onion Mashed Potatoes? Let me know what you think, and leave a comment below! Don’t forget to take a picture of your recreation and tag me on Instagram. I love to see all of your photos!