This Is Our All-Time Most Popular Potato Casserole

It came to J. Kenji López-Alt in a dream, this dish that combines Hasselback potatoes with a classic French potato gratin. Inspired, he got out of bed and started peeling potatoes at 2 a.m.

Since then, it’s been featured in his first cookbook, “The Food Lab,” and on New York Times Cooking, where it’s been one of our most popular potato recipes since publication, garnering nearly 10,000 five-star reviews.

Watch him make his Hasselback potato gratin, and learn why he uses russets for an extra crispy exterior and creamy interior, the importance of salt and why potatoes and French fries are never quite as good when you reheat them.

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