French Onion Mashed Potatoes

No holiday table is complete without mashed potatoes, but you don’t have to make them the same way every year. Mashed potatoes are one of the easiest sides to put your own spin on when you want to shake up your Turkey Day menu.

These French onion mashed potatoes take the classic side and turn up the volume with sweet, caramelized onions and nutty Gruyere cheese folded in. They’re an easy way to add a little excitement to the holiday spread while still serving a comforting classic that everyone expects.

Ingredients for French Onion Mashed Potatoes

• Butter: You’ll use butter twice in this recipe, first to slowly caramelize the onions, then again to make the mashed potatoes rich and creamy. Use unsalted butter so you can control the sodium in both parts of the recipe.
• Onions: Yellow onions are our go-to for caramelized onions because they have plenty of natural sweetness that develops into deep, rich flavor as they cook. Chop the onions rather than slicing them into rings or half-moons as you might for French onion soup. Smaller pieces mix more evenly into the mashed potatoes, ensuring you get a little caramelized onion in every bite.
• Potatoes: Yukon Gold potatoes are an excellent choice for mashed potatoes because they have a naturally creamy texture. Russets also work well and will give you a lighter, fluffier mash. This recipe calls for peeled potatoes, but you can leave the skins on if you prefer a more rustic mash.
• Sour cream: Sour cream adds richness and a little tang to balance the buttery potatoes and sweet caramelized onions.
• Milk: Whole milk gives the mashed potatoes a rich, creamy texture, but 2% works just as well if that’s what you have. For the smoothest mash, warm the milk in a small saucepan or in the microwave before adding it. Cold milk can cool down the potatoes, causing them to firm up before you’re finished mashing.
• Gruyere cheese: Gruyere’s nutty, slightly sweet flavor is a natural match for caramelized onions, and gives these mashed potatoes their French onion soup–inspired personality.
• Chives: Minced chives add a pop of green and a mild, fresh onion bite to the finished potatoes.

Directions

Step 1: Caramelize the onions

Melt 2 tablespoons of butter in a large skillet over medium heat. Add the chopped onions and cook them for five to six minutes or until they begin to soften and lightly brown, stirring occasionally.

Reduce the heat to medium-low and continue cooking for 35 to 45 minutes, stirring every five minutes, until the onions are deep brown and very soft and jammy. Season them with salt.

Editor’s Tip: Be patient! Properly caramelized onions take time. If they start browning too quickly, turn the heat down further and keep stirring every few minutes.

Step 2: Cook the potatoes

Meanwhile, place the potatoes in a stockpot and add enough water to cover them. Add 1 teaspoon of salt and bring them to a boil. Reduce the heat and cook, uncovered, until the potatoes are tender when pierced with a fork, about 20 to 25 minutes. Drain the water and return the potatoes to the pot.

Editor’s Tip: Start the potatoes in cold, salted water. The cold water helps them cook evenly, while the salt seasons the potatoes from the inside out.

Step 3: Make the mashed potatoes

Add the butter, sour cream, the remaining teaspoon of salt, and the pepper to the warm potatoes. Beat the mixture until it’s blended, then gradually beat in the milk until the potatoes are creamy. Fold in the caramelized onions, shredded Gruyere and minced chives.

Transfer the mashed potatoes to a serving bowl and garnish them with additional chives and melted butter, if desired.

Recipe Variations

• Add bacon: Crispy bacon takes this mash straight into loaded-potato territory. Pan-fry or microwave a few strips, then crumble them into the potatoes or sprinkle them over the top before serving.
• Switch up the cheese: No Gruyere? No problem. Try shredded Swiss or fontina for a similar melty texture, or go with Gouda or sharp white cheddar for a bolder flavor.
• Stir in roasted garlic: Roast a head of garlic while the onions caramelize, then squeeze the soft cloves into the potatoes before mashing them. The garlic turns mellow and slightly sweet as it roasts, bringing even more savory flavor to these potatoes.
• Finish with a cheesy crust: For serious French onion vibes, transfer the mashed potatoes to a baking dish and sprinkle more shredded cheese over the top. Broil them until the cheese is melted, bubbly and golden.

How to Store French Onion Mashed Potatoes

Let the French onion mashed potatoes cool slightly, then transfer them to an airtight container and refrigerate them for up to four days.

To reheat the mashed potatoes, place them in a covered baking dish and warm them in a 350°F oven until they’re heated through, stirring occasionally. You can also reheat individual portions in the microwave. If the potatoes seem a little dry, stir in a splash of warm milk to bring back their creamy texture.

Can you freeze French onion mashed potatoes?

Yes! French onion mashed potatoes can be frozen for up to two months. Let the potatoes cool completely, then transfer them to an airtight, freezer-safe container or freezer bag and pop them in the freezer.

Thaw the potatoes overnight in the fridge. Reheat them in the oven or microwave.

Can you make French onion mashed potatoes ahead of time?

French onion mashed potatoes are a great make-ahead side dish for the holidays or any big dinner. Prepare the mashed potatoes as directed, then transfer them to a greased baking dish, cover and refrigerate them for up to three days.

Let the potatoes sit at room temperature while the oven preheats. Bake them, covered, at 350° until they’re heated through. Give them a stir before serving them, and add a splash of warm milk if they need a little help getting creamy again.

French Onion Mashed Potato Tips

How do you keep French onion mashed potatoes creamy?

For creamy French onion mashed potatoes, don’t overwork them. Mash them with a handheld masher or potato ricer (an essential Thanksgiving gadget) just until they’re smooth, then mix in the warm milk. For make-ahead or reheated potatoes, stirring in a little extra warm milk before serving them can help restore creaminess.

How do you keep mashed potatoes warm for serving?

For a holiday meal, transfer the mashed potatoes to a covered, heat-safe dish, and keep them warm in a 200° oven until you’re ready to serve them. Dot the top with a few pats of butter, then cover the dish to prevent the potatoes from drying out.

What can you serve with French onion mashed potatoes?

French onion mashed potatoes are right at home next to a Thanksgiving turkey or glazed ham. For a cozy Sunday dinner, serve them with roast beef, pork chops or slow-cooker short ribs, plus a green vegetable or crisp salad.

What can you do with leftover French onion mashed potatoes?

Leftover French onion mashed potatoes are too good to let go to waste! Turn them into golden potato cakes by mixing them into a savory pancake batter, or use them as a creamy topping for a skillet shepherd’s pie. Of course, the leftovers are also delicious on their own!