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Creamy Baked Scalloped Potatoes with Gruyère and Thyme

This creamy baked scalloped potatoes recipe is comforting and easy, featuring Gruyère cheese and thyme for a delightful flavor balance.
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Prep Time 20 minutes
Cook Time 1 hour 10 minutes
Total Time 1 hour 30 minutes
Servings: 6 servings
Course: Side Dish, Vegetable
Cuisine: American
Calories: 400
Ingredients Method Notes

Ingredients
  

Main Ingredients
  • 2.5 to 3 pounds Yukon Gold or russet potatoes, peeled (or scrubbed well if you prefer skins on), thinly sliced (about 1/8-inch)
  • 2 tablespoons unsalted butter
  • 1 small onion, finely chopped (optional but lovely)
  • 2 cloves garlic, minced
  • 3 tablespoons all-purpose flour
  • 2 cups whole milk (or 1 cup milk + 1 cup half-and-half for extra creaminess)
  • 1 cup heavy cream (optional — you can use all milk)
  • 1.5 teaspoons kosher salt, plus more to taste
  • 0.5 teaspoon black pepper
  • 0.25 teaspoon ground nutmeg (optional)
  • 1.5 to 2 cups grated Gruyère cheese, divided
  • 1 tablespoon fresh thyme leaves, chopped (or 1 teaspoon dried thyme)
  • 0.5 cup grated Parmesan or Pecorino Romano (optional, for a golden top)
  • 2 tablespoons fresh parsley, chopped (for garnish)

Method
 

Preparation
  1. Preheat the oven to 375°F (190°C) and lightly butter a 9x13-inch baking dish.
  2. Slice the potatoes using a mandoline or sharp knife, keeping slices about 1/8-inch thick.
Making the Sauce
  1. In a medium saucepan, melt the butter over medium heat. Add the chopped onion and cook for 3–4 minutes until softened. Stir in the garlic and cook for 30 seconds longer.
  2. Sprinkle the flour over the onion and whisk for about a minute.
  3. Slowly pour in the milk and cream while whisking to prevent lumps. Bring to a gentle simmer, stirring constantly until thickened slightly, about 2–4 minutes.
  4. Add salt, pepper, and nutmeg. Remove from heat and stir in half of the grated Gruyère until melted.
Layering the Potatoes
  1. Arrange a layer of potato slices across the bottom of the dish. Sprinkle with salt and thyme, then ladle some sauce over the potatoes.
  2. Repeat layering potatoes, salt, thyme, and sauce until top of the dish, reserving about 1/2 cup of sauce.
Baking
  1. Pour remaining sauce over assembled potatoes. Top with remaining Gruyère and Parmesan.
  2. Cover tightly with foil and bake for 35 minutes. Remove foil and continue baking for an additional 25–35 minutes until top is bubbling and golden.
  3. If the top browns too quickly, tent with foil loosely.
Serving
  1. Let the dish rest for 10–15 minutes before serving. Garnish with chopped parsley and more thyme leaves.

Notes

Make-ahead option: Assemble in the baking dish, refrigerate for up to 24 hours, and bake as directed, adding extra time. Thin, consistent slices are essential for even cooking. If sauce appears thin before baking, that is normal as it thickens during cooking.