French Onion Mashed Potatoes

Rich, savory, tangy and sweet, this show-stopping side is a mash-up (literally) of two classic dishes that just about everyone loves. Though the recipe only asks for 1 teaspoon of thyme, it’s a critical component here; if you can’t find fresh, use ½ teaspoon dried thyme.
Prep Time
Cook Time


  •  6 Tablespoons Danish Creamery European Style Garlic Salt Butter, divided
  •  2 small onions, diced
  •  Kosher salt
  •  freshly ground black pepper
  •  1 teaspoon fresh thyme leaves
  •  3 pounds Yukon gold potatoes, peeled and cut into 2-inch chunks
  •  ¾ cup whole milk
  •  1 cup sour cream
  •  2 cups shredded gruyere, divided
  •  ½ cup grated Parmesan, divided


  • Preheat oven to 400°F. Butter a 2-quart baking dish and set aside.
  • Heat 2 tablespoons butter in a large skillet over medium-low heat. Add onions, season with salt and pepper and cook, stirring occasionally, until onions are deeply golden and very soft, about 30 minutes. Stir in thyme and set aside.
  • Place potatoes in a large pot and cover with an inch of cold water. Bring to a boil, season generously with salt, then cover and reduce to a simmer. Cook until fork tender, about 15 minutes.
  • Meanwhile, gently heat milk, remaining 4 tablespoons garlic butter, 1 teaspoon kosher salt and ¼ teaspoon black pepper in a small saucepan. Remove from heat and whisk in sour cream.
  • Drain potatoes in a colander and return to the warm pot. Let sit a few minutes to dry out. Pass potatoes through a ricer into a large bowl, then mix in warm cream mixture. Stir in 1½ cups shredded gruyere and half the caramelized onions; season with salt and black pepper.
  • Transfer to prepared baking dish and spread in an even layer. Sprinkle with remaining caramelized onions, remaining ½ cup gruyere and grated parmesan. Bake until warmed through, about 20 minutes. Broil for 2-3 minutes, or until top is golden brown. Serve hot.

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