Ingredients:

  • 2 lbs (900g) Yukon Gold potatoes, peeled and thinly sliced
  • 1 medium yellow onion, thinly sliced
  • 2 cloves garlic, minced
  • 4 tbsp (57g) unsalted butter, melted
  • 1/4 cup (30g) all-purpose flour
  • 3 cups (710ml) whole milk
  • 1/2 cup (120ml) heavy cream
  • 1 tsp kosher salt (or to taste)
  • 1/2 tsp black pepper (freshly ground, if possible)
  • 1/4 tsp ground nutmeg (optional)
  • 1 cup (115g) shredded Gruyere cheese (or cheddar)

Instructions:

  1. Slice potatoes and onions thinly. Mince the garlic.
  2. Melt butter in a saucepan. Whisk in flour and cook for 1 minute. Gradually whisk in milk and cream. Bring to a simmer, stirring constantly until thickened.
  3. Stir in salt, pepper, and nutmeg. Remove from heat.
  4. Layer half the potatoes in the baking dish, followed by half the onions and garlic. Pour half the cream sauce over. Repeat layers.
  5. Sprinkle Gruyere (or cheddar) over the top.
  6. Bake in a preheated oven at 375°F (190°C) for 45-55 minutes, or until potatoes are tender and the top is golden brown and bubbly. Test for doneness by inserting a knife – it should go in easily.
  7. Let stand for 10 minutes before serving.