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Cheesy Scalloped Potatoes

Thinly sliced potatoes and onion are layered with a creamy roux-based sauce, sharp cheddar, and Parmesan, then baked until tender and golden. This comforting side dish serves 6–8 people.
Print Recipe
Prep Time 20 minutes
Cook Time 1 hour 5 minutes
Total Time 1 minute
Servings: 6 servings
Ingredients Method Notes

Ingredients
  

Potatoes and Cheese
  • 3 pounds Russet or Yukon Gold potatoes, peeled or scrubbed and sliced about 1/8 inch thick
  • 1 medium Medium yellow onion, thinly sliced
  • 1 1/2 cups Sharp cheddar cheese, shredded
  • 1/2 cup Parmesan cheese, finely shredded
Creamy Sauce
  • 4 tablespoons Unsalted butter
  • 1/4 cup All-purpose flour
  • 2 cups Whole milk
  • 1 cup Half-and-half or heavy cream
Seasonings
  • 1 teaspoon Kosher salt
  • 1/2 teaspoon Freshly ground black pepper
  • 1/2 teaspoon Garlic powder or 1 minced garlic clove
Garnish
  • 1 tablespoon Fresh parsley or chives, chopped

Method
 

Step-by-Step
  1. Heat the oven to 375°F and grease a 9-by-13-inch baking dish.
  2. Slice the potatoes evenly into pieces about 1/8 inch thick. Do not rinse the slices, because their natural starch helps thicken the sauce.
  3. Melt the butter in a saucepan over medium heat. Whisk in the flour and cook for about 1 minute.
  4. Gradually whisk in the milk and half-and-half or heavy cream. Add the salt, pepper, and garlic, then simmer for 3–5 minutes, whisking often, until lightly thickened.
  5. Arrange one-third of the potatoes and onion in the prepared baking dish. Pour over one-third of the sauce and sprinkle with some cheddar and Parmesan, then repeat for two more layers.
  6. Cover the dish tightly with foil and bake for 45–50 minutes.
  7. Remove the foil and bake for another 20–25 minutes, until the potatoes are tender when pierced with a knife and the cheese is browned and bubbling.
  8. Rest the casserole for 10–15 minutes before serving. Garnish with chopped parsley or chives if desired.

Notes

Use evenly sliced potatoes and keep the casserole covered during the first part of baking so the center cooks through. Resting for 10–15 minutes allows the sauce to set and makes the portions easier to serve.