Ingredients:

  • 5 lb / 1.15 kg Starchy potatoes (e.g., Russet or Yukon Gold), peeled and sliced thinly (approx. 1/8 inch)
  • 1 clove Garlic, whole (for rubbing the dish)
  • 1/2 tsp Kosher Salt (for seasoning layers)
  • 1/4 tsp Freshly Ground Black Pepper
  • 3 tbsp / 42 g Unsalted Butter (plus extra for greasing)
  • 1 small Shallot, finely minced
  • 2 cloves Garlic, minced
  • 3 tbsp / 24 g All-Purpose Flour
  • 4 cups / 946 ml Whole Milk, warmed
  • 1/2 cup / 120 ml Heavy Cream
  • 1/2 tsp Kosher Salt
  • 1/4 tsp White Pepper (optional)
  • 1/4 tsp Freshly Grated Nutmeg
  • 1 sprig Fresh Thyme

Instructions:

  1. Preparation: Peel and slice the potatoes uniformly thin (1/8 inch). Immediately rinse slices under cold water to remove excess starch, then pat them thoroughly dry. Preheat oven to 375°F (190°C). Grease a 9x13 inch baking dish generously with butter, and rub the surface with the whole garlic clove.
  2. Start the Béchamel: In a medium saucepan, melt the butter over medium heat. Add the minced shallot and sauté until softened (about 3 minutes). Add the minced garlic and thyme sprig, cooking for 1 minute until fragrant.
  3. Make the Roux: Sprinkle in the flour and whisk continuously for 1–2 minutes until a smooth, pale roux forms. Cook out the raw flour flavor.
  4. Add Liquids: Slowly pour in the warm whole milk while whisking constantly to prevent lumps. Once smooth, stir in the heavy cream.
  5. Simmer and Season: Bring the sauce to a gentle simmer, whisking frequently, until it thickens enough to coat the back of a spoon (5–7 minutes). Remove the thyme sprig. Season generously with salt, pepper, and nutmeg. Taste and adjust seasoning.
  6. Assemble: Arrange one-third of the potato slices in a single, overlapping layer in the prepared baking dish. Ladle one-third of the béchamel sauce evenly over the potatoes and sprinkle lightly with salt and pepper.
  7. Repeat: Repeat the layering process twice more, ensuring the top layer of Scalloped Potatoes is completely submerged or well-coated by the remaining sauce.
  8. Bake (Covered): Cover the dish tightly with foil. Bake for 45 minutes at 375°F (190°C) to ensure the potatoes cook through evenly.
  9. Bake (Uncovered): Remove the foil and continue baking for another 25–35 minutes, or until the top is deeply golden brown and the potatoes are fork-tender.
  10. Rest: Remove from the oven and allow the dish to rest for 15 minutes before serving. This crucial step allows the starches to set and prevents a watery result.