Mashed Potato Gratin

This mashed potato gratin absolutely wowed our recipe testers who reveled in the ultra-creamy, buttery cheesiness of panko-topped mashed potatoes. Try it for your next family dinner and watch everybody swoon. 

An oval serving dish filled with mashed potato gratin and a portion of it on a plate beside the dish.

Adapted from Valerie Rice | Lush Life | Prospect Park Books, 2021

My Belgium-born mother certainly knows her way around the potato. It was a mainstay in her childhood garden and cold cellar (“kelder” in Dutch), making it a staple at most meals. She always tops creamy mounds of whipped potatoes (never made without egg yolk and nutmeg) with crispy breadcrumbs. Although she lives two hours away (three with Southern California traffic), I feel like she’s in the kitchen with me every time I make one of her recipes. This is a particular favorite, especially for entertaining, because you can get away with making it in advance and still serve warm potatoes.–Valerie Rice

Mashed Potato Gratin

An oval serving dish filled with mashed potato gratin and a portion of it on a plate beside the dish.
This mashed potato gratin is for anyone who revels in the ultra-creamy, buttery cheesiness of panko-topped mashed potatoes. Try it for your next family dinner and watch everybody swoon.
Valerie Rice

Prep 35 mins
Cook 35 mins
Total 1 hr 10 mins
Sides
American
8 servings
291 kcal
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Ingredients 

  • 4 (about 2 pounds) russet potatoes peeled and cut into 1-inch (25-mm) pieces
  • 3 1/2 teaspoons Diamond Crystal kosher salt (or 2 teaspoons Morton kosher salt)
  • 2 1/4 cups half-and-half
  • 1 1/2 sticks (6 oz) unsalted butter
  • 1/2 teaspoon ground white pepper
  • 1/4 teaspoon freshly grated nutmeg
  • 1 large egg yolk
  • 1/2 cup panko bread crumbs
  • 1/4 cup freshly grated Parmesan cheese
  • 1 tablespoon chopped fresh parsley
  • 1 tablespoon extra-virgin olive oil

Directions
 

  • Preheat the oven to 350°F (177C).
  • Place potatoes in a large pot and add 2 teaspoons salt (1 teaspoon, if using Morton) and enough cold water to cover by 2 inches (5 cm). Bring the potatoes to a boil over high heat, then reduce heat and simmer until tender, 10 to 20 minutes.
  • Drain the potatoes and return to the hot pot. Place over low heat and simmer until dry, then use a potato masher to thoroughly mash the potatoes.
  • In a small saucepan over medium heat, warm the half-and-half, butter, pepper, and nutmeg until the butter melts. Remove from the heat.
  • Place the egg yolk in a small bowl. Ladle in a small scoop of the warm milk mixture and whisk to temper the yolk. Whisk the tempered egg yolk back into the milk mixture.
  • Slowly whisk the milk mixture into the potatoes. The potato mixture will be very loose. Season with the remaining 1 1/2 teaspoons salt (1 teaspoon, if using Morton).
  • Butter an 8x12-inch (20-by 30-cm) oval gratin baking dish.
  • In a small bowl, combine panko, parmesan, parsley, and oil. Pour the mashed potatoes into the dish. Sprinkle with the breadcrumb mixture. (Can be made 6 hours ahead. Cover and refrigerate.)
  • Bake gratin until the top is golden brown and heated through, 35 to 45 minutes. If made ahead, allow for an extra 10 minutes of cooking time.

    TESTER TIP: If your gratin seems a little loose after baking, let it cool for a few minutes. It should firm right up.

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Notes

*Why are my mashed potatoes gluey and gummy?

Overworking potatoes is the number one reason for that gluey or gummy texture that we've all experienced. Potatoes are pretty much all starch, and starch doesn't like to be vigorously handled. There are a few ways to avoid this, fortunately. Always use warm liquids when mashing—it will absorb better and faster so that you don't overwork those spuds. Mash by hand or use a potato ricer. A food processor is just too much power and will lead to that dreaded potato paste. 

Show Nutrition

Serving: 1portionCalories: 291kcal (15%)Carbohydrates: 6g (2%)Protein: 4g (8%)Fat: 28g (43%)Saturated Fat: 17g (106%)Trans Fat: 1gCholesterol: 96mg (32%)Sodium: 400mg (17%)Potassium: 111mg (3%)Fiber: 1g (4%)Sugar: 1g (1%)Vitamin A: 868IU (17%)Vitamin C: 1mg (1%)Calcium: 125mg (13%)Iron: 1mg (6%)

Recipe Testers' Reviews

PURE HEAVEN. I'll never make regular mashed potatoes again. I made half the amount which should have been enough for four people, but two of us devoured the entire thing! We just couldn't stop. This mashed potato gratin is luscious and silky and the crumb topping just takes it to the next level. It's such a simple recipe, and definitely, one to make ahead for a dinner party. Your guests will love you for this one.

I served this with lamb and rapini for Easter dinner and it was a gorgeous meal.

Creamy and delicious! At first, I was concerned as the prepared mixture looked more like a thin potato soup. I ventured on, hoping it would turn into a smooth and luxurious finished product—which it did! The browned, crunchy, cheesy crumb topping complemented the taste of the smooth potatoes beneath. Not too heavy, although rich. And, plenty of leftovers for our small family of two. I served the mashed potato gratin with a hearty roast brisket, which was perfect, as the seasonings of both didn't compete with one another. Although I ended up with a sink full of dishes, I'll make it again.

This mashed potato gratin is a nice twist on everyday mashed potatoes. They're creamy, and in addition to flavor, the topping adds wonderful crispness to the bite. This works well as a make-ahead potato dish, and everyone loved it. If you like mashed potatoes, you’ll love this dish.

That said, for me, this is a special occasion dish. It’s a real treat with the added cream, butter, and egg yolk. I do try to make classic dishes such as mashed potatoes with a nod to health, so while making it, I wondered if I could sub some half-and-half with milk, and what if I put a little less butter? I find potatoes are really good with healthy substitutions—to a point—and with this recipe, I wondered how much I could sub to have it with a little less decadence. But at some point, that defeats the purpose of a dish like this.

Everyone loved the dish as the recipe is written, though I can’t imagine anyone that wouldn’t love it. The three of us almost finished this recipe intended for 8. There was a small amount left, but probably not enough for 1 person. We had it with steak, salad, and bread. In my experience, you always need more of this kind of dish – it’s delicious and easy to take more than a “portion,” so I'd be more generous in the serving sizes and make it for just 4 people.

When I read this recipe for mashed potato gratin I thought, "how could this not be amazing?" And, well, it couldn't NOT be amazing. It takes mashed potatoes up several notches so they become extremely rich, you have to beware. Rich, creamy, silky, and full of flavor. The topping, just parmesan, panko bread crumbs, and parsley, was genius.

The recipe itself wasn't complicated or tricky though I'd never mashed dry potatoes before. Since I have an old-style potato masher with a bunch of holes, I couldn't get them super smooth but that was okay. However, the recipe says to "whisk" the milk mixture into the potatoes and there was no whisking anything into my potatoes, so I mixed and mashed it in. I was concerned at that point because they were extremely liquidy. I poured them into the baking dish and baked them for 35 minutes. The top was brown, so I took them out. The top looked awfully jiggly and I was worried. They didn't really hold up at all when spooned onto the plate but they were so darned good. The potatoes did firm up as they cooled and the leftovers haven't been liquidy at all. I don't know if less half-and-half should be used. Two and a quarter cups seems like an awful lot of milk for two pounds of potatoes. But, again, that taste!

What drew me to this recipe was the method of making the mashed potatoes ahead of time, as a casserole, then baking them for serving. This was a new method and one that worked well.

This mashed potato gratin is very creamy. This lovely texture comes about by adding half-and-half, butter, and egg yolk. The addition of a topping is a nice change as well. Using parmesan cheese adds some extra saltiness and yumminess to the final product. Overall, this is an easy recipe that makes for a great change-up to your usual mashed potatoes.


Originally published May 08, 2021

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