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Creamy French onion mashed potatoes in a ceramic bowl topped with caramelized onions, melted Gruyere, and fresh chives

French Onion Mashed Potatoes with Caramelized Onions & Gruyère

Emily S
Velvety Yukon Gold mashed potatoes folded with 40-minute caramelized onions, beef broth, fresh thyme, and melted Gruyère cheese.
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Prep Time 15 minutes
Cook Time 45 minutes
Total Time 1 hour
Course Dinner, Side Dish
Cuisine American, French-Inspired
Servings 8 servings
Calories 403 kcal

Equipment

  • 5-quart stockpot
  • Large Dutch oven or heavy-bottomed skillet
  • Potato masher or potato ricer
  • Chef's knife
  • Box grater
  • Silicone spatula

Ingredients
  

  • 3 lbs Yukon Gold potatoes peeled and cut into 1-inch chunks (1.36 kg)
  • 5 tbsp unsalted butter divided (71 g)
  • 2 large yellow onions thinly sliced (about 450 g)
  • 1/2 cup low-sodium beef broth 120 ml
  • 1 tsp fresh thyme leaves finely chopped
  • 3/4 cup heavy cream warmed (180 ml)
  • 1/3 cup full-fat sour cream room temperature (80 g)
  • 1 1/2 cups Gruyère cheese freshly shredded (170 g)
  • 1 1/2 tsp kosher salt divided, plus more to taste
  • 1/2 tsp freshly ground black pepper
  • 2 tbsp fresh chives finely chopped, for garnish

Instructions
 

  • Melt 3 tablespoons of the unsalted butter in a large Dutch oven or heavy-bottomed skillet over medium-low heat. Add the sliced yellow onions and 1/2 teaspoon kosher salt, then cook for 35 to 40 minutes, stirring every 5 minutes, until deeply browned and jammy.
    Sliced yellow onions caramelizing in melted butter inside a cream Dutch oven
  • Stir the fresh thyme leaves and low-sodium beef broth into the caramelized onions, scraping up any browned bits from the bottom of the pan. Simmer for 2 to 3 minutes until the liquid reduces into a glossy glaze, then remove from heat.
    Caramelized onions deglazed with beef broth and fresh thyme simmering into a glossy glaze
  • Place the peeled Yukon Gold potato chunks in a 5-quart stockpot, cover with cold water by 1 inch, and stir in 1 teaspoon kosher salt. Bring to a boil over high heat, reduce to a steady simmer, and cook for 15 to 18 minutes until fork-tender. Drain well, return the potatoes to the hot pot, and let them steam-dry over low heat for 60 seconds.
    Boiled Yukon Gold potato chunks steaming dry in a stainless steel stockpot
  • Remove the pot from heat and mash the dried potatoes until smooth. Fold in the remaining 2 tablespoons butter, warmed heavy cream, room-temperature sour cream, and black pepper until velvety.
    Mashing steam-dried Yukon Gold potatoes with melted butter and warmed heavy cream
  • Stir in the freshly shredded Gruyère cheese and two-thirds of the caramelized onions until the cheese melts completely into the warm mash. Taste and adjust salt if needed.
    Folding shredded Gruyere cheese and caramelized onions into creamy mashed potatoes
  • Transfer the mashed potatoes to a warm serving bowl, spoon the remaining caramelized onions over the center, scatter with chopped fresh chives, and serve hot.
    Spooning caramelized onions and fresh chives over French onion mashed potatoes in a serving bowl

Notes

For a deeper crust, transfer the finished potatoes to a buttered baking dish, top with an extra 1/4 cup Gruyère, and broil for 2 to 3 minutes until bubbling.
Calculated from USDA FoodData Central values for Yukon Gold potatoes, unsalted butter, yellow onions, low-sodium beef broth, heavy cream, sour cream, and Gruyere cheese across 8 servings.

Nutrition

Serving: 280gCalories: 403kcalCarbohydrates: 36gProtein: 12gFat: 24gSaturated Fat: 15gPolyunsaturated Fat: 1gMonounsaturated Fat: 7gCholesterol: 74mgSodium: 387mgPotassium: 765mgFiber: 4gSugar: 4gVitamin A: 425IUVitamin C: 20mgCalcium: 215mgIron: 2mg
Keyword Caramelized Onion Mashed Potatoes, French Onion Mashed Potatoes, Holiday Side Dish
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