Ingredients
2 tablespoons unsalted butter
1 small onion, chopped fine
2 garlic cloves, minced
3 cups heavy cream
1 cup whole milk
4 sprigs fresh thyme
2 bay leaves
2 teaspoons salt
½ teaspoon pepper
4 pounds russet potatoes, peeled and sliced ⅛ inch thick
4 ounces cheddar cheese, shredded (1 cup)
2 tablespoons minced fresh chives
Directions
1
Adjust oven rack to lower-middle position and heat oven to 350 degrees. Melt butter in Dutch oven over medium heat. Add onion and cook until softened and lightly browned, 5 to 7 minutes. Stir in garlic and cook until fragrant, about 30 seconds. Stir in cream, milk, thyme sprigs, bay leaves, salt, and pepper. Stir in potatoes and bring to simmer. Reduce heat to low, cover, and cook, stirring occasionally, until potatoes are almost tender (paring knife can be slipped in and out of potato slice with some resistance), 15 to 20 minutes.
2
Discard thyme sprigs and bay leaves. Smooth surface of potatoes, then sprinkle with cheddar. Transfer pot to oven and bake, uncovered, until sauce is thickened and potatoes are tender, about 15 minutes.
3
Remove pot from oven and heat broiler element. Return pot to oven and broil until bubbling around edges and top is spotty brown, 5 to 10 minutes. Let cool for 15 minutes. Sprinkle with chives and serve.