Ingredients:

  • 2.5 lbs (1.1 kg) Russet potatoes, peeled and thinly sliced (about 1/8 inch thick)
  • 1 medium yellow onion, thinly sliced
  • 2 cloves garlic, minced
  • 4 tablespoons (57g) unsalted butter
  • 4 tablespoons (32g) all-purpose flour
  • 3 cups (710ml) whole milk
  • 1/2 teaspoon ground nutmeg
  • 1/4 teaspoon white pepper
  • 1 teaspoon salt (or to taste)
  • 1/2 teaspoon black pepper (or to taste)
  • 1/2 cup (50g) grated Gruyère cheese (optional)

Instructions:

  1. Slice potatoes and onion thinly. Mince the garlic.
  2. Melt butter in a saucepan. Whisk in flour and cook for 1 minute. Gradually whisk in milk until smooth. Bring to a simmer, stirring constantly. Reduce heat and simmer until thickened, about 5-7 minutes. Stir in nutmeg, white pepper, salt, and black pepper.
  3. Preheat oven to 375°F (190°C). Grease the baking dish. Arrange a layer of potato slices on the bottom of the dish, overlapping slightly. Top with a layer of onion and minced garlic. Drizzle with some of the cream sauce. Repeat layers until all potatoes and onions are used, ending with a layer of sauce.
  4. Cover the dish with foil and bake for 30 minutes. Remove foil, sprinkle with Gruyère cheese (if using), and bake for another 20-30 minutes, or until potatoes are tender and top is golden brown.
  5. Let the scalloped potatoes rest for 10 minutes before serving. This allows the sauce to thicken slightly.