Creamy au gratin potatoes are the definition of comfort done right. Thinly sliced Yukon gold potatoes are layered in a rich garlic-thyme cream sauce and baked until tender, bubbling, and lightly golden on top. This version is indulgent without being heavy, and elegant enough for a special occasion — the kind of side dish that quietly steals the show.

They’re especially perfect alongside steak, where their richness balances beautifully with a simple green vegetable and a good glass of wine.

Ingredients:

  • 3 tablespoons unsalted butter, divided
  • 3 garlic cloves, minced
  • ½ teaspoon fresh thyme, finely chopped (plus more for finishing)
  • 2 cups heavy cream
  • 1½ teaspoons kosher salt, divided
  • 1 tablespoon warm water
  • 1 teaspoon cornstarch
  • 2 ounces Parmesan cheese, finely grated
  • 6 ounces mild white Cheddar cheese, shredded, divided
  • 2 pounds Yukon gold potatoes, thinly sliced (about ⅛-inch thick)
  • ½ teaspoon freshly ground black pepper

Directions:

Prepare the oven and baking dish
Preheat the oven to 325°F. Butter an 11-by-7-inch baking dish with 1 tablespoon of the butter and set aside.

Make the cream sauce
In a medium saucepan, melt the remaining butter over medium heat. Add the garlic and thyme and cook, stirring constantly, until fragrant, about 1 minute.

Pour in the cream and add ½ teaspoon of the salt. Whisk to combine, then lower the heat and let the mixture gently warm for about 5 minutes to allow the flavors to develop.

Thicken the sauce
In a small bowl, whisk together the warm water and cornstarch until smooth. Slowly whisk this mixture into the warm cream sauce and cook, stirring constantly, until it thickens slightly, about 1 minute.

Stir in the Parmesan and ½ cup of the Cheddar cheese, whisking until melted and smooth. Remove the sauce from heat.

Assemble the potatoes
In a large bowl, toss the sliced potatoes with the remaining salt and black pepper. Arrange the potatoes in even layers in the prepared baking dish, then pour the warm cream sauce evenly over the top.

Sprinkle with the remaining Cheddar cheese.

Bake and rest
Bake until the potatoes are tender and the top is lightly golden, 50 minutes to 1 hour. Let the dish rest for about 15 minutes before serving, then finish with a few fresh thyme leaves.

REALM Hosting Notes

These potatoes can be assembled a few hours ahead and baked just before serving, making them ideal for a relaxed, restaurant-style dinner at home.