Potatoes Au Gratin

Name: Potatoes Au Gratin (Classic French Recipe)
Prep time: 15 min
Cook time: 1 h
Total time: 1 h 15 min
Yield: 6 servings
Cuisine: French
Ingredients: Butter to grease the baking dish; 2½ lb Russet potatoes ((3 to 4), peeled and very thinly sliced); 1½ teaspoons salt; ¼ teaspoon freshly ground black pepper; 1 cup (4 oz) finely grated Parmigiano-Reggiano; 2¼ cups heavy cream; Fresh thyme, (for serving (optional))

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Potatoes au gratin is a classic French potato casserole layered with Russet potatoes, Parmigiano-Reggiano, and heavy cream, baked until tender and golden brown. Despite its fancy name, this elegant dish is surprisingly straightforward to make at home.

🌍French 🏷️Potatoes au gratin

Total

1h 15m

Servings

6

Recipe Source

View original recipe

From Onceuponachef

Ingredients

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Butter to grease the baking dish
2½ lb Russet potatoes ((3 to 4), peeled and very thinly sliced)
1½ teaspoons salt
¼ teaspoon freshly ground black pepper
1 cup (4 oz) finely grated Parmigiano-Reggiano
2¼ cups heavy cream
Fresh thyme, (for serving (optional))optional

7 Ingredients

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Instructions

1
Preheat the oven to 350°F (175°C) and set an oven rack in the middle position. Grease an 8-in (20-cm) or 2-qt/2L baking dish with butter.
2
In a large mixing bowl, toss the potatoes with the salt and pepper until evenly coated.
3
Arrange some of the potato slices, edges overlapping, in a single layer on the bottom of the prepared baking dish. Sprinkle a quarter of the cheese over the potatoes, and then pour a quarter of the cream over the cheese. Repeat with the remaining potatoes, cheese, and cream, forming 4 layers. Pour any leftover cream over top.
4
Place in the oven and bake, uncovered, for 60 to 75 minutes, or until the potatoes are tender when pierced with a knife and golden brown on top. Let the dish settle on the counter for about ten minutes. Sprinkle with fresh thyme, if using, and then serve.

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Tips & Notes

Pro tips

Slice potatoes uniformly thin (about 1/8 inch) using a mandoline or sharp knife so they cook evenly and tender in the 60–75 minute window.
Layer potatoes, cheese, and cream in 4 equal layers to ensure even seasoning and cream distribution throughout the dish.
Let the finished gratin rest for 10 minutes before serving—this allows the cream to set slightly and makes plating neater.
Place the oven rack in the middle position to ensure even browning on top and thorough cooking throughout without burning the bottom.

Substitutions

Russet potatoes → Yukon Gold (will be slightly firmer; still tender when pierced)
Parmigiano-Reggiano → Gruyère or Emmental (nuttier flavor, melts smoothly)
Heavy cream → half-and-half mixed with whole milk (lighter result, less rich)

Storage & make-ahead

Store leftovers covered in the refrigerator for up to 3 days. Reheat covered in a 350°F oven for 15–20 minutes until warmed through.

Equipment

mandoline or sharp slicing knife · 8-inch or 2-quart baking dish

Common Questions

Can I make potatoes au gratin ahead of time?

Yes. Assemble the dish up to 4 hours before baking, cover with plastic wrap, and refrigerate. Add 5–10 minutes to the baking time if baking from cold.