Description

These Caramelized Onion Mashed Potatoes are a rich and creamy twist on the classic mashed potato side dish. Featuring deeply caramelized onions, melted gruyere cheese, and a smooth blend of butter and half-and-half, they deliver a perfect balance of savory and sweet flavors. Ideal for holiday dinners or elevating any weeknight meal, this recipe combines comfort with elegance in every bite.

Ingredients

For the Onions

2 tablespoons olive oil
1 tablespoon butter
3–4 large yellow onions, sliced 1/4 inch thick
1/4 teaspoon kosher salt

For the Potatoes

3 pounds russet potatoes, peeled and diced
4 cloves garlic, peeled and smashed
2 teaspoons kosher salt (divided), plus more to taste
4 tablespoons unsalted butter, plus more for serving
3/4 cup half and half
1/4 teaspoon black pepper
4 oz gruyere cheese, grated (plus more for topping)
Thinly sliced chives, for garnish
Fresh thyme, for garnish

Cook Mode Prevent your screen from going dark

Instructions

Make the Caramelized Onions: Heat a large pan with a lid over medium-low heat. Add 2 tablespoons olive oil and 1 tablespoon butter. Stir in the sliced onions and sprinkle 1/4 teaspoon kosher salt over them. Cover and cook for 30-40 minutes, stirring every 5 minutes until the onions turn a deep caramelized golden brown.
Cook the Potatoes: Place diced potatoes, smashed garlic, and 1 teaspoon kosher salt into a large pot. Cover with cold water and bring to a boil. Cook until the potatoes are fork tender, about 15-20 minutes. Drain well.
Mash the Potatoes: Return drained potatoes and garlic to the warm pot. Mash using a potato masher or hand mixer until smooth.
Add Ingredients to Potatoes: Blend in the remaining 1 teaspoon kosher salt, 4 tablespoons unsalted butter, half and half, and black pepper. Mash until creamy and fully combined.
Incorporate Onions and Cheese: Fold half of the caramelized onions and all of the grated gruyere cheese into the mashed potatoes until well combined. Add more half and half if needed for creaminess. Adjust salt and pepper to taste.
Serve: Transfer mashed potatoes to a serving dish. Top with the remaining caramelized onions, additional grated gruyere, thinly sliced chives, fresh thyme, and a pat of butter before serving.

Notes

Use russet potatoes for the best texture and creaminess in mashed potatoes.
Caramelize onions slowly over low heat to avoid burning and develop deep sweetness.
Gruyere cheese adds a nutty, creamy flavor that melts beautifully into the potatoes.
For extra creaminess, adjust the amount of half and half to your liking.
Leftovers can be refrigerated for up to 3 days and reheated gently with a splash of half and half.