Creamy Potato Gratin Thyme (Print Version)

Thinly sliced potatoes baked with cream, cheeses, and fresh thyme for a rich, golden side.

# Recipe Ingredients:

→ Vegetables

01 - 3.3 lbs Yukon Gold or Russet potatoes, peeled and thinly sliced (1/16 inch)
02 - 1 medium yellow onion, thinly sliced (optional)

→ Dairy

03 - 1 2/3 cups heavy cream
04 - 3/4 cup plus 2 tbsp whole milk
05 - 1/2 cup grated Gruyère cheese (plus extra for topping)
06 - 1/3 cup grated Parmesan cheese
07 - 2 tbsp unsalted butter (plus extra for greasing)

→ Herbs & Seasoning

08 - 2 to 3 sprigs fresh thyme leaves, plus extra for garnish
09 - 2 cloves garlic, minced
10 - 1/4 tsp ground nutmeg
11 - 1 tsp fine sea salt
12 - 1/2 tsp freshly ground black pepper

# Directions:

01 - Preheat the oven to 350°F. Generously butter a 2-quart gratin dish to prevent sticking.
02 - In a saucepan, combine heavy cream, whole milk, minced garlic, ground nutmeg, sea salt, black pepper, and thyme leaves. Warm gently over medium heat until just steaming without boiling. Remove from heat.
03 - Arrange half of the sliced potatoes in overlapping layers in the prepared dish. Add half the sliced onions if using, followed by half the Gruyère and Parmesan cheeses.
04 - Pour half of the warm cream mixture evenly over the layered ingredients.
05 - Repeat layers with remaining potatoes, onions, Gruyère, and Parmesan. Press down gently to level the layers.
06 - Dot the surface with butter and sprinkle additional Gruyère and a few thyme leaves. Cover tightly with aluminum foil.
07 - Bake covered for 40 minutes. Remove foil and continue baking an additional 20 minutes until the top is golden brown and bubbling.
08 - Allow the gratin to rest for 10 minutes before serving. Garnish with fresh thyme leaves.

# Expert Advice:

01 -
  • It uses simple pantry staples but tastes like something you'd order at a bistro tucked away in Lyon.
  • The layers turn impossibly creamy inside while the top gets crispy and golden, giving you two textures in every forkful.
  • You can assemble it hours ahead and just slide it into the oven when guests arrive, no last-minute panic required.
02 -
  • Slice your potatoes as evenly as possible—a mandoline makes this foolproof, but a sharp knife and patience work just as well.
  • Don't let the cream boil or it can curdle and ruin the silky texture you're aiming for.
  • Press down on the layers before baking so the liquid reaches every crevice, otherwise you'll end up with dry spots that never soften.
03 -
  • Use a mandoline set to 2–3 mm for perfectly even slices that cook at the same rate and layer beautifully.
  • Let the gratin rest after baking—it may seem impatient, but those 10 minutes let the layers firm up so you get clean, elegant servings instead of a soupy mess.
  • Save any leftover cream mixture and drizzle it over the top halfway through baking if the potatoes look dry.

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