Creamy Mashed Potatoes with Caramelized Onions

Upgrade your mashed potatoes with this mouthwatering Caramelized Onion Mashed Potatoes recipe. With about 16 generous servings, this easy-to-make side is ideal for a crowd.

Easy and delicious mashed potato with onion

Mashed potatoes are a reliable crowd-pleaser, and these caramelized onion mashed potatoes take the classic to the next level. Silky, creamy potatoes combined with deeply flavored, sweet caramelized onions make each bite irresistible.

This recipe yields enough to serve a large gathering, making it a perfect potluck or holiday side. The contrast of smooth potatoes and rich onion flavor pairs well with many mains.

Ingredients in caramelized onion mashed potatoes

Potatoes bring potassium, fiber, vitamin B6 and some protein, while the caramelized onions add depth and sweetness. The list below covers both the onion and potato components.

Onions

• Onions: 2 lbs yellow onions, sliced. Yellow onions caramelize nicely, though other varieties will work.
• Butter: 1/4 cup butter (salted preferred) for flavor.
• Olive oil: 2 tbsp to help cook the onions evenly.
• Sugar: 2 tsp to encourage browning and enhance sweetness.
• Salt & pepper: 1 tsp salt and 1/2 tsp pepper to season.

Potatoes

• Potatoes: 3.5 lbs russet potatoes, peeled and cubed for boiling.
• Butter: 1/4 cup butter, cut into cubes, for creaminess.
• Sour cream: 8 oz sour cream — key for richness and texture.
• Milk: 1/2 cup milk (whole milk preferred) to loosen the mash.
• Salt & pepper: 1 tsp salt and 1/2 tsp pepper to taste.

Kitchen tools used to make this mashed potatoes and onions recipe

Gather these tools before you start:

• Cutting board and knife
• Large skillet and spatula
• Large pot or saucepan and strainer
• Potato masher or ricer
• Measuring spoons and cups (1/2 tsp, 1 tsp, 1 tbsp, 1/4 cup, 1/2 cup)

How to make these caramelized onion mashed potatoes

This dish takes about one hour total. The caramelized onions require patience, but the result is worth it.

1. Slice the onions thinly (half-moon slices work well). Heat a large skillet over medium and add the butter and olive oil. When melted, add the onions and cook for 15 minutes, stirring every few minutes so they soften evenly.

2. After the initial cooking, add the sugar, salt, and pepper. Continue to cook the onions for another 20–30 minutes, stirring occasionally, until they turn a deep golden brown and caramelize. Remove from heat and set aside.

3. While the onions caramelize, bring a large pot of water to a boil. Add the peeled, cubed potatoes and cook until fork-tender, about 12 minutes. Drain thoroughly.

4. Return the drained potatoes to the pot and mash with a potato masher or pass through a ricer. Add the cubed butter, sour cream, and milk, and mash until smooth and creamy. Season with salt and pepper to taste.

5. Fold the caramelized onions and their buttery juices into the mashed potatoes, mixing until evenly combined. Taste and adjust seasoning as needed. Serve warm.

Wondering about garnishes?

These mashed potatoes are delicious on their own, but you can set up a potato bar to let guests customize their bowls. Popular toppings:

• Chopped green onions
• Crispy bacon bits
• Extra sour cream
• Shredded cheese
• Fresh herbs (parsley, chives)
• Additional butter

How do restaurants make their mashed potatoes so good?

Sour cream is often the secret: it adds body, creaminess, and a subtle tang that lifts the flavor.

Is it better to caramelize onions in butter or oil?

Use both: butter gives flavor while oil raises the smoke point and helps the onions cook evenly without burning.

What can I add to these onion mashed potatoes?

Feel free to customize. Add green onions, crispy bacon, sour cream, shredded cheese, fresh herbs, or extra butter for more richness.

If you liked this recipe, you’ll want to try these!

Try other comforting potato dishes or explore a collection of potato recipes for more ideas.

• Glazed Sweet Potatoes
• Healthier Sweet Potato Casserole
• Lightened Scalloped Potatoes
• Potato Sweet Corn Chowder

All recipes by Erin Morrissey and photos by Sierra Inn.