Ingredients
Scale
- 2 ½ pounds Yukon Gold potatoes, peeled and thinly sliced (about 1/8 inch thick)
- 1 ½ cups heavy cream
- 1 cup whole milk
- 3 garlic cloves, minced
- 1 teaspoon fresh thyme leaves (or ½ teaspoon dried thyme)
- 1 ½ cups Gruyere cheese, grated
- 1 cup Parmesan cheese, finely grated
- 2 tablespoons unsalted butter, softened
- Salt and freshly ground black pepper to taste
- Pinch of nutmeg (optional, but Mama Lou swore by it!)
Ingredient substitutions: If Gruyere isn’t available, Emmental or a good Swiss cheese works well as a substitute. For a lighter version, you can swap heavy cream with half-and-half, but be mindful it may affect richness and texture. Parmesan can be replaced with Pecorino Romano for a sharper bite.
Instructions
- Preheat your oven to 375°F (190°C). Butter a 9×13-inch baking dish generously to ensure the gratin doesn’t stick and to add a hint of richness around the edges.
- Peel and thinly slice the Yukon Gold potatoes. I find using a mandoline slicer makes this step easier and ensures even cooking. Mama Lou always insisted on uniform slices, saying it was the secret to perfect texture.
- In a medium saucepan, combine the heavy cream, whole milk, minced garlic, thyme, salt, pepper, and a pinch of nutmeg. Warm over medium heat until it just begins to simmer—do not boil. This infused cream will soak into the potatoes, making every layer flavorful.
- Arrange a single layer of potato slices in the bottom of the prepared baking dish. Pour a small amount of the warm cream mixture over the layer, then sprinkle with a mix of Gruyere and Parmesan cheeses.
- Repeat this layering process — potatoes, cream, cheese — until all ingredients are used, finishing with a generous layer of cheese on top. This top layer is where the magic happens: it will crisp and brown beautifully.
- Dot the surface with small pieces of softened butter. This little addition helps create that irresistible golden crust.
- Cover the dish tightly with aluminum foil and bake for 45 minutes. This allows the potatoes to steam and absorb the flavors gently.
- After 45 minutes, remove the foil and bake uncovered for an additional 20-25 minutes, or until the top is bubbly and golden brown. You’ll know it’s ready when a knife inserted into the center slides in easily and the cheese crust crackles invitingly.
- Remove from oven and let the gratin rest for 10-15 minutes before serving. This resting time lets the layers set and makes it easier to cut beautiful portions, just like Mama Lou taught me.
- Prep Time: 15 minutes
- Cook Time: 30 minutes
- Category: Main Dish
- Method: Cooking
- Cuisine: International