Recipe information
Yield
serves 4
Ingredients
2 tablespoons butter
1 large or 2 medium sweet onions, such as Vidalia, thinly sliced
Salt and pepper
1/2 teaspoon ground thyme, or dried if ground isn’t available
1 bay leaf, fresh or dried
2 pounds baby Yukon Gold potatoes or fingerling potatoes
1/2 to 2/3 cup cream
1/2 cup grated Parmigiano-Reggiano cheese
1/2 pound grated Gruyère or other Swiss cheese
Preparation
Step 1
Heat a skillet with the butter over medium heat. Add the onions, season with salt, pepper, the thyme, and the bay leaf, and cook until very soft and sweet and lightly caramelized, about 20 minutes. Remove the bay leaf.
Step 2
While the onions cook, place the potatoes in a pot and cover with water. Bring to a boil, salt the water, and cook until tender, 12 to 15 minutes. Drain and return to the hot pot. Mash the potatoes with the cream, season with salt and pepper, and mash in the Parm cheese.
Step 3
Preheat the broiler. Arrange the mashed potatoes in individual gratin dishes or a shallow casserole. Top the potatoes with the onions and Gruyère cheese. Brown the gratins under the hot broiler until bubbly, about 2 minutes.
